<PAGE>

                                                                     Exhibit 4.6

THIS WARRANT HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED OR ANY STATE SECURITIES LAWS. NO SALE OR DISPOSITION MAY BE EFFECTED
WITHOUT (i) EFFECTIVE REGISTRATION STATEMENTS RELATED THERETO, (ii) AN OPINION
OF COUNSEL OR OTHER EVIDENCE, REASONABLY SATISFACTORY TO THE COMPANY, THAT SUCH
REGISTRATIONS ARE NOT REQUIRED, (iii) RECEIPT OF NO-ACTION LETTERS FROM THE
APPROPRIATE GOVERNMENTAL AUTHORITIES, OR (iv) OTHERWISE COMPLYING WITH THE PRO
VISIONS OF SECTION 7 OF THIS WARRANT.

                  ONVIA.COM, INC. (f/k/a Megadepot.com, Inc.)

                          WARRANT TO PURCHASE SHARES
                          OF SERIES A PREFERRED STOCK

     THIS CERTIFIES THAT, for value received, MEIER MITCHELL & COMPANY and its
assignees are entitled to subscribe for and purchase that number of the fully
paid and nonassessable shares of Series A Preferred Stock (as adjusted pursuant
to Section 4 hereof, the "Shares") of ONVIA.COM, INC. (f/k/a Megadepot.com,
Inc.), a Washington corporation (the "Company"), as is determined pursuant to
the next paragraph hereof at the price per share as is determined pursuant to
the next paragraph hereof (such price and such other price as shall result, from
time to time, from the adjustments specified in Section 4 hereof is herein
referred to as the "Warrant Price"), subject to the provisions and upon the
terms and conditions hereinafter set forth.  As used herein, (a) the term
"Series Preferred" shall mean the Company's presently authorized Series A
Preferred Stock, and any stock into or for which such Series A Preferred Stock
may hereafter be converted or exchanged, and after the automatic conversion of
the Series A Preferred Stock to Common Stock shall mean the Company's Common
Stock, (b) the term "Date of Grant" shall mean August 5, 1999, and (c) the term
"Other Warrants" shall mean any other warrants issued by the Company in
connection with the transaction with respect to which this Warrant was issued,
and any warrant issued upon transfer or partial exercise of or in lieu of this
Warrant.  The term "Warrant" as used herein shall be deemed to include Other
Warrants unless the context clearly requires otherwise.

          The number of Shares granted pursuant to this Warrant shall be the
nearest whole number obtained by dividing $450,000 by the Exercise Price. The
Exercise Price shall be determined according to subparagraphs (A), (B), (C) or
(D) below:

               (A)  Subject to subparagraphs (B), (C) and (D) below, if, on or
prior to October 31, 1999, the Company completes a private offering of its
equity securities, the aggregate gross proceeds from which exceed $5,000,000
(whether in one transaction or in a series of transactions after the date of
this Warrant and excluding the conversion of debt to equity) (a "Qualified
Financing"), then the Exercise Price shall be determined as follows:
<PAGE>

                         Exercise Price = X + (A/B) (Y-X)

               Where:    X =  $1.17;

                         Y =  The product obtained by multiplying .80 times the
                              lesser of (i) the price per share of equity
                              securities (expected to be Series B Preferred
                              Stock) sold in the Qualified Financing (the
                              "Qualified Valuation") and (ii) the quotient
                              obtained by dividing 300,000,000 by the number of
                              shares (on a common stock equivalent basis) of the
                              Company outstanding immediately after the closing
                              of the Qualified Financing (assuming the exercise
                              or conversion into common stock of the Company of
                              all outstanding warrants, options, convertible
                              securities, and other rights to acquire common
                              stock of the Company);

                         A =  2; and

                         B =  The number of months (rounded to the nearest whole
                              number) which have elapsed from May 1, 1999, to
                              the date of the closing of the Qualified
                              Financing.

               (B)  Notwithstanding subparagraph (A) above, if the Warrant is
exercised after December 31, 1999 and if the Exercise Price calculated in
subparagraph (A) exceeds the quotient obtained by dividing 100,000,000 by the
number of shares (on a common stock equivalent basis) of the Company outstanding
immediately after the closing of the Qualified Financing (assuming the exercise
or conversion into common stock of the Company of all outstanding warrants,
options, convertible securities, and other rights to acquire common stock of the
Company) (the "Adjusted Valuation") and if the Company has not signed up at
least 700,000 customer members by December 31, 1999, then the Exercise Price
shall be the Adjusted Valuation.  The Company shall deliver to Meier Mitchell &
Company a certificate certifying as to the number of customer members as of
December 31, 1999, as promptly as possible and in no event later than January
15, 2000.

               (C)  Notwithstanding subparagraph (A) above, if the Warrant is
exercised (i) after the closing of a Qualified Financing, but on or prior to
December 31, 1999, and (ii) in connection with a merger, acquisition or sale of
all or substantially all of the assets of the Company (the "Merger Event") where
the Acquisition Valuation (as defined below) is less than the Qualified
Valuation, then the Exercise Price shall be the Adjusted Valuation. For purposes
of this provision, the term "Acquisition Valuation" means the quotient obtained
by dividing the aggregate consideration received by the Company in the Merger
Event by the number of shares (on a common stock equivalent basis) of the
Company outstanding immediately prior to the closing of such Merger Event
(assuming the exercise or conversion into

                                      -2-
<PAGE>

common stock of the Company of all outstanding warrants, options, convertible
securities, and other rights to acquire common stock of the Company)

               (D)  If the Company does not complete the Qualified Financing on
or prior to October 31, 1999, or if this Warrant is exercised on or prior to
October 31, 1999 and the Company has not completed the Qualified Financing, then
the Exercise Price shall be $1.17.

     1.   Term. The purchase right represented by this Warrant is exercisable,
          ----
in whole or in part, at any time and from time to time from the Date of Grant
through the later of (i) ten (10) years after the Date of Grant or (ii) five (5)
years after the closing of the Company's initial public offering of its Common
Stock ("IPO") effected pursuant to a Registration Statement on Form S-1 (or its
successor) filed under the Securities Act of 1933, as amended (the "Act"),
provided that if there is no IPO within ten (10) years of the Grant Date, then
this Warrant shall terminate ten (10) years after the Date of Grant.  This
Warrant will automatically and without further action become a warrant to
purchase shares of the Company's Common Stock, subject to all of the terms and
provisions of this Warrant, upon the effectiveness of the Registration Statement
filed by the Company in connection with its IPO.

     2.   Method of Exercise; Payment; Issuance of New Warrant.  Subject to
          ----------------------------------------------------
Section 1 hereof, the purchase right represented by this Warrant may be
exercised by the holder hereof, in whole or in part and from time to time, at
the election of the holder hereof, by (a) the surrender of this Warrant (with
the notice of exercise substantially in the form attached hereto as Exhibit A-1
duly completed and executed) at the principal office of the Company and by the
payment to the Company, by certified or bank check, or by wire transfer to an
account designated by the Company (a "Wire Transfer") of an amount equal to the
then applicable Warrant Price multiplied by the number of Shares then being
purchased;  (b) if in connection with a registered public offering of the
Company's securities, the surrender of this Warrant (with the notice of exercise
form attached hereto as Exhibit A-2 duly completed and executed) at the
principal office of the Company together with notice of arrangements reasonably
satisfactory to the Company for payment to the Company either by certified or
bank check or by Wire Transfer from the proceeds of the sale of shares to be
sold by the holder in such public offering of an amount equal to the then
applicable Warrant Price per share multiplied by the number of Shares then being
purchased;  or (c) exercise of the "net issuance" right provided for in Section
10.2 hereof.  The person or persons in whose name(s) any certificate(s)
representing shares of Series Preferred shall be issuable upon exercise of this
Warrant shall be deemed to have become the holder(s) of record of, and shall be
treated for all purposes as the record holder(s) of, the shares represented
thereby (and such shares shall be deemed to have been issued) immediately prior
to the close of business on the date or dates upon which this Warrant is
exercised.  In the event of any exercise of the rights represented by this
Warrant, certificates for the shares of stock so purchased shall be delivered to
the holder hereof as soon as possible and in any event within thirty (30) days
after such exercise and, unless this Warrant has been fully exercised or
expired, a new Warrant representing the portion of the Shares, if any, with
respect to which this Warrant shall not then have been exercised shall also be
issued to the holder hereof as soon as possible and in any event within such
thirty-day period;  provided, however, at such time as the Company is subject to
the reporting requirements of the Securities Exchange Act of 1934, as amended,
if requested by the holder of this Warrant, the Company shall cause its transfer
agent to deliver the certificate

                                      -3-
<PAGE>

representing Shares issued upon exercise of this Warrant to a broker or other
person (as directed by the holder exercising this Warrant) within the time
period required to settle any trade made by the holder after exercise of this
Warrant.

     3.   Stock Fully Paid; Reservation of Shares.  All Shares that may be
          ---------------------------------------
issued upon the exercise of the rights represented by this Warrant will, upon
issuance pursuant to the terms and conditions herein, be fully paid and
nonassessable, and free from all taxes, liens and charges with respect to the
issue thereof. During the period within which the rights represented by this
Warrant may be exercised, the Company will at all times have authorized, and
reserved for the purpose of the issue upon exercise of the purchase rights
evidenced by this Warrant, a sufficient number of shares of its Series Preferred
to provide for the exercise of the rights represented by this Warrant and a
sufficient number of shares of its Common Stock to provide for the conversion of
the Series Preferred into Common Stock.

     4.   Adjustment of Warrant Price and Number of Shares.  The number and kind
          ------------------------------------------------
of securities purchasable upon the exercise of this Warrant and the Warrant
Price shall be subject to adjustment from time to time upon the occurrence of
certain events, as follows:

          (a)  Reclassification or Merger.  In case of any reclassification or
               --------------------------
change of securities of the class issuable upon exercise of this Warrant (other
than a change in par value, or from par value to no par value, or from no par
value to par value, or as a result of a subdivision or combination), or in case
of any merger of the company with or into another corporation (other than a
merger with another corporation in which the Company is the acquiring and the
surviving corporation and which does not result in any reclassification or
change of outstanding securities issuable upon exercise of this Warrant), or in
case of any sale of all or substantially all of the assets of the Company, the
Company, or such successor or purchasing corporation, as the case may be, shall
duly execute and deliver to the holder of this Warrant a new Warrant (in form
and substance satisfactory to the holder of this Warrant), or the Company shall
make appropriate provision without the issuance of a new Warrant, so that the
holder of this Warrant shall have the right to receive, at a total purchase
price not to exceed that payable upon the exercise of the unexercised portion of
this Warrant, and in lieu of the shares of Series Preferred theretofore issuable
upon exercise of this Warrant, (i) the kind and amount of shares of stock, other
securities, money and property receivable upon such reclassification, change,
merger or sale by a holder of the number of shares of Series Preferred then
purchasable under this Warrant, or (ii) in the case of such a merger or sale in
which the consideration paid consists all or in part of assets other than
securities of the successor or purchasing corporation, at the option of the
Holder of this Warrant, the securities of the successor or purchasing
corporation having a value at the time of the transaction equivalent to the
valuation of the Series Preferred at the time of the transaction.  Any new
Warrant shall provide for adjustments that shall be as nearly equivalent as may
be practicable to the adjustments provided for in this Section 4.  The
provisions of this subparagraph (a) shall similarly apply to successive
reclassifications, changes, mergers and transfers.

          (b)  Subdivision or Combination of Shares.  If the Company at any time
               ------------------------------------
while this Warrant remains outstanding and unexpired shall subdivide or combine
its outstanding shares of Series Preferred, the Warrant Price shall be
proportionately decreased and the number of Shares issuable hereunder shall be
proportionately increased in the case of a subdivision and

                                      -4-
<PAGE>

the Warrant Price shall be proportionately increased and the number of Shares
issuable hereunder shall be proportionately decreased in the case of a
combination.

          (c)  Stock Dividends and Other Distributions.  If the Company at any
               ---------------------------------------
time while this Warrant is outstanding and unexpired shall (i) pay a dividend
with respect to Series Preferred payable in Series Preferred, then the Warrant
Price shall be adjusted, from and after the date of determination of
shareholders entitled to receive such dividend or distribution, to that price
determined by multiplying the Warrant Price in effect immediately prior to such
date of determination by a fraction (A) the numerator of which shall be the
total number of shares of Series Preferred outstanding immediately prior to such
dividend or distribution, and (B) the denominator of which shall be the total
number of shares of Series Preferred outstanding immediately after such dividend
or distribution;  or (ii) make any other distribution with respect to Series
Preferred (except any distribution specifically provided for in Sections 4(a)
and 4(b)), then, in each such case, provision shall be made by the Company such
that the holder of this Warrant shall receive upon exercise of this Warrant a
proportionate share of any such dividend or distribution as though it were the
holder of the Series Preferred (or Common Stock issuable upon conversion
thereof) as of the record date fixed for the determination of the shareholders
of the Company entitled to receive such dividend or distribution.

          (d)  Adjustment of Number of Shares.  Upon each adjustment in the
               ------------------------------
Warrant Price, the number of Shares of Series Preferred purchasable hereunder
shall be adjusted, to the nearest whole share, to the product obtained by
multiplying the number of Shares purchasable immediately prior to such
adjustment in the Warrant Price by a fraction, the numerator of which shall be
the Warrant Price immediately prior to such adjustment and the denominator of
which shall be the Warrant Price immediately thereafter.

          (e)  Antidilution Rights.  The other antidilution rights, if any,
               -------------------
applicable to the Shares of Series Preferred purchasable hereunder are set forth
in the Company's articles of incorporation, as amended through the Date of
Grant, a true and complete copy of which is attached hereto as Exhibit B (the
"Charter").  Such antidilution rights shall not be restated, amended, modified
or waived in any manner that is adverse to the holder hereof without such
holder's prior written consent.  The Company shall promptly provide the holder
hereof with any restatement, amendment, modification or waiver of the Charter
promptly after the same has been made.

     5.   Notice of Adjustments.  Whenever the Warrant Price or the number of
          ---------------------
Shares purchasable hereunder shall be adjusted pursuant to Section 4 hereof, the
Company shall make a certificate signed by its chief financial officer setting
forth, in reasonable detail, the event requiring the adjustment, the amount of
the adjustment, the method by which such adjustment was calculated, and the
Warrant Price and the number of Shares purchasable hereunder after giving effect
to such adjustment, and shall cause copies of such certificate to be mailed
(without regard to Section 13 hereof, by first class mail, postage prepaid) to
the holder of this Warrant.  In addition, whenever the conversion price or
conversion ratio of the Series Preferred shall be adjusted, the Company shall
make a certificate signed by its chief financial officer setting forth, in
reasonable detail, the event requiring the adjustment, the amount of the
adjustment, the method by which such adjustment was calculated, and the
conversion price or ratio of the Series

                                      -5-
<PAGE>

Preferred after giving effect to such adjustment, and shall cause copies of such
certificate to be mailed (without regard to Section 13 hereof, by first class
mail, postage prepaid) to the holder of this Warrant.

     6.   Fractional Shares.  No fractional shares of Series Preferred will be
          -----------------
issued in connection with any exercise hereunder, but in lieu of such fractional
shares the Company shall make a cash payment therefor based on the fair market
value of the Series Preferred on the date of exercise as reasonably determined
in good faith by the Company's Board of Directors.

     7.   Compliance with Act; Disposition of Warrant or Shares of Series
          ---------------------------------------------------------------
Preferred.
---------

          (a)  Compliance with Act.  The holder of this Warrant, by acceptance
               -------------------
hereof, agrees that this Warrant, and the shares of Series Preferred to be
issued upon exercise hereof and any Common Stock issued upon conversion thereof
are being acquired for investment and that such holder will not offer, sell or
otherwise dispose of this Warrant, or any shares of Series Preferred to be
issued upon exercise hereof or any Common Stock issued upon conversion thereof
except under circumstances which will not result in a violation of the Act or
any applicable state securities laws.  Upon exercise of this Warrant, unless the
Shares being acquired are registered under the Act and any applicable state
securities laws or an exemption from such registration is available, the holder
hereof shall confirm in writing that the shares of Series Preferred so purchased
(and any shares of Common Stock issued upon conversion thereof) are being
acquired for investment and not with a view toward distribution or resale in
violation of the Act and shall confirm such other matters related thereto as may
be reasonably requested by the Company.  This Warrant and all shares of Series
Preferred issued upon exercise of this Warrant and all shares of Common Stock
issued upon conversion thereof (unless registered under the Act and any
applicable state securities laws) shall be stamped or imprinted with a legend in
substantially the following form:

"THE SECURITIES EVIDENCED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES
ACT OF 1933, AS AMENDED, OR ANY STATE SECURITIES LAWS. NO SALE OR DISPOSITION
MAY BE EFFECTED WITHOUT (i) EFFECTIVE REGISTRATION STATEMENTS RELATED THERETO,
(ii) AN OPINION OF COUNSEL OR OTHER EVIDENCE, REASONABLY SATISFACTORY TO THE
COMPANY, THAT SUCH REGISTRATIONS ARE NOT REQUIRED, (iii) RECEIPT OF NO-ACTION
LETTERS FROM THE APPROPRIATE GOVERNMENTAL AUTHORITIES, OR (iv) OTHERWISE
COMPLYING WITH THE PROVISIONS OF SECTION 7 OF THE WARRANT UNDER WHICH THESE
SECURITIES WERE ISSUED, DIRECTLY OR INDIRECTLY."

     Said legend shall be removed by the Company, upon the request of a holder,
at such time as the restrictions on the transfer of the applicable security
shall have terminated. In addition, in connection with the issuance of this
Warrant, the holder specifically represents to the Company by acceptance of this
Warrant as follows:

               (1)  The holder is aware of the Company's business affairs and
financial condition, and has acquired information about the Company sufficient
to reach an informed and knowledgeable decision to acquire this Warrant. The
holder is acquiring this

                                      -6-
<PAGE>

Warrant for its own account for investment purposes only and not with a view to,
or for the resale in connection with, any "distribution" thereof in violation of
the Act.

               (2)  The holder understands that this Warrant has not been
registered under the Act in reliance upon a specific exemption therefrom, which
exemption depends upon, among other things, the bona fide nature of the holder's
investment intent as expressed herein.

               (3)  The holder further understands that this Warrant must be
held indefinitely unless subsequently registered under the Act and qualified
under any applicable state securities laws, or unless exemptions from
registration and qualification are otherwise available. The holder is aware of
the provisions of Rule 144, promulgated under the Act.

               (4)  The holder is an "accredited investor" as such term is
defined in Rule 501 of Regulation D promulgated under the Act.

          (b)  Disposition of Warrant or Shares.  With respect to any offer,
               --------------------------------
sale or other disposition of this Warrant or any shares of Series Preferred
acquired pursuant to the exercise of this Warrant prior to registration of such
Warrant or shares, the holder hereof agrees to give written notice to the
Company prior thereto, describing briefly the manner thereof, together with a
written opinion of such holder's counsel, or other evidence, if reasonably
satisfactory to the Company, to the effect that such offer, sale or other
disposition may be effected without registration or qualification (under the Act
as then in effect or any federal or state securities law then in effect) of this
Warrant or such shares of Series Preferred or Common Stock and indicating
whether or not under the Act certificates for this Warrant or such shares of
Series Preferred to be sold or otherwise disposed of require any restrictive
legend as to applicable restrictions on transferability in order to ensure
compliance with such law. Upon receiving such written notice and reasonably
satisfactory opinion or other evidence, the Company, as promptly as practicable
but no later than fifteen (15) days after receipt of the written notice, shall
notify such holder that such holder may sell or otherwise dispose of this
Warrant or such shares of Series Preferred or Common Stock, all in accordance
with the terms of the notice delivered to the Company. If a determination has
been made pursuant to this Section 7(b) that the opinion of counsel for the
holder or other evidence is not reasonably satisfactory to the Company, the
Company shall so notify the holder promptly with details thereof after such
determination has been made. Notwithstanding the foregoing, this Warrant or such
shares of Series Preferred or Common Stock may, as to such federal laws, be
offered, sold or otherwise disposed of in accordance with Rule 144 or 144A under
the Act, provided that the Company shall have been furnished with such
information as the Company may reasonably request to provide a reasonable
assurance that the provisions of Rule 144 or 144A have been satisfied. Each
certificate representing this Warrant or the shares of Series Preferred thus
transferred (except a transfer pursuant to Rule 144 or 144A) shall bear a legend
as to the applicable restrictions on transferability in order to ensure
compliance with such laws, unless in the aforesaid opinion of counsel for the
holder, such legend is not required in order to ensure compliance with such
laws. The Company may issue stop transfer instructions to its transfer agent in
connection with such restrictions.

                                      -7-
<PAGE>

          (c)  Applicability of Restrictions.  Neither any restrictions of any
               -----------------------------
legend described in this Warrant nor the requirements of Section 7(b) above
shall apply to any transfer of, or grant of a security interest in, this Warrant
(or the Series Preferred or Common Stock obtainable upon exercise thereof) or
any part hereof (i) to a partner of the holder if the holder is a partnership or
to a member of the holder if the holder is a limited liability company, (ii) to
a partnership of which the holder is a partner or to a limited liability company
of which the holder is a member, or (iii) to any affiliate of the holder if the
holder is a corporation;  provided, however, in any such transfer, if
applicable, the transferee shall on the Company's request agree in writing to be
bound by the terms of this Warrant as if an original holder hereof.

     8.   Rights as Shareholders; Information.  No holder of this Warrant, as
          -----------------------------------
such, shall be entitled to vote or receive dividends or be deemed the holder of
Series Preferred or any other securities of the Company which may at any time be
issuable on the exercise hereof for any purpose, nor shall anything contained
herein be construed to confer upon the holder of this Warrant, as such, any of
the rights of a shareholder of the Company or any right to vote for the election
of directors or upon any matter submitted to shareholders at any meeting
thereof, or to receive notice of meetings, or to receive dividends or
subscription rights or otherwise until this Warrant shall have been exercised
and the Shares purchasable upon the exercise hereof shall have become
deliverable, as provided herein.  Notwithstanding the foregoing, the Company
will transmit to the holder of this Warrant such information, documents and
reports as are generally distributed to the holders of any class or series of
the securities of the Company concurrently with the distribution thereof to the
shareholders.

     9.   [Reserved]

     10.  Additional Rights.
          -----------------

     10.1 Acquisition Transactions.  The Company shall provide the holder of
          ------------------------
this Warrant with at least twenty (20) days' written notice prior to closing
thereof of the terms and conditions of any of the following transactions (to the
extent the Company has notice thereof):  (i) the sale, lease, exchange,
conveyance or other disposition of all or substantially all of the Company's
property or business, or (ii) its merger into or consolidation with any other
corporation (other than a wholly-owned subsidiary of the Company), or any
transaction (including a merger or other reorganization) or series of related
transactions, in which more than 50% of the voting power of the Company is
disposed of.

     10.2 Right to Convert Warrant into Stock:  Net Issuance.
          --------------------------------------------------

          (a)  Right to Convert.  In addition to and without limiting the rights
               ----------------
of the holder under the terms of this Warrant, the holder shall have the right
to convert this Warrant or any portion thereof (the "Conversion Right") into
shares of Series Preferred (or Common Stock if the Series Preferred has been
automatically converted into Common Stock) as provided in this Section 10.2 at
any time or from time to time during the term of this Warrant.  Upon exercise of
the Conversion Right with respect to a particular number of shares subject to
this Warrant (the "Converted Warrant Shares"), the Company shall deliver to the
holder (without payment by the holder of any exercise price or any cash or other
consideration) that number of shares of fully

                                      -8-
<PAGE>

paid and nonassessable Series Preferred (or Common Stock if the Series Preferred
has been automatically converted into Common Stock) as is determined according
to the following formula:

     X = B-A
         ---
          Y

     Where:  X =  the number of shares of Series Preferred (or Common Stock if
                  the Series Preferred has been automatically converted to
                  Common Stock) that shall be issued to holder

             Y =  the fair market value of one share of Series Preferred (or
                  Common Stock if the Series Preferred has been automatically
                  converted to Common Stock)

             A =  the aggregate Warrant Price of the specified number of
                  Converted Warrant Shares immediately prior to the exercise of
                  the Conversion Right (i.e., the number of Converted Warrant
                  Shares multiplied by the Warrant Price)

             B =  the aggregate fair market value of the specified number of
                  Converted Warrant Shares (i.e., the number of Converted
                  Warrant Shares multiplied by the fair market value of one
                  Converted Warrant Share)

     No fractional shares shall be issuable upon exercise of the Conversion
Right, and, if the number of shares to be issued determined in accordance with
the foregoing formula is other than a whole number, the Company shall pay to the
holder an amount in cash equal to the fair market value of the resulting
fractional share on the Conversion Date (as hereinafter defined).  For purposes
of Section 9 of this Warrant, shares issued pursuant to the Conversion Right
shall be treated as if they were issued upon the exercise of this Warrant.

          (b)  Method of Exercise.  The Conversion Right may be exercised by the
               ------------------
holder by the surrender of this Warrant at the principal office of the Company
together with a written statement (which may be in the form of Exhibit A-1 or
Exhibit A-2 hereto) specifying that the holder thereby intends to exercise the
Conversion Right and indicating the number of shares subject to this Warrant
which are being surrendered (referred to in Section 10.2(a) hereof as the
Converted Warrant Shares) in exercise of the Conversion Right.  Such conversion
shall be effective upon receipt by the Company of this Warrant together with the
aforesaid written statement, or on such later date as is specified therein (the
"Conversion Date"), and, at the election of the holder hereof, may be made
contingent upon the closing of the sale of the Company's Common Stock to the
public in a public offering pursuant to a Registration Statement under the Act
(a "Public Offering").  Certificates for the shares issuable upon exercise of
the Conversion Right and, if applicable, a new warrant evidencing the balance of
the shares remaining subject to this Warrant, shall be issued as of the
Conversion Date and shall be delivered to the holder within thirty (30) days
following the Conversion Date.

                                      -9-
<PAGE>

           (c)  Determination of Fair Market Value.  For purposes of this
                ----------------------------------
Section 10.2, "fair market value" of a share of Series Preferred (or Common
Stock if the Series Preferred has been automatically converted into Common
Stock) as of a particular date (the "Determination Date") shall mean:

                (i)  If the Conversion Right is exercised in connection with and
contingent upon a Public Offering, and if the Company's Registration Statement
relating to such Public Offering ("Registration Statement") has been declared
effective by the Securities and Exchange Commission, then the initial "Price to
Public" specified in the final prospectus with respect to such offering.

                (ii) If the Conversion Right is not exercised in connection with
and contingent upon a Public Offering, then as follows:

           (A)  If traded on a securities exchange, the fair market value of the
Common Stock shall be deemed to be the average of the closing prices of the
Common Stock on such exchange over the 30-day period ending five business days
prior to the Determination Date, and the fair market value of the Series
Preferred shall be deemed to be such fair market value of the Common Stock
multiplied by the number of shares of Common Stock into which each share of
Series Preferred is then convertible;

           (B)  If traded on the Nasdaq Stock Market or other over-the-counter
system, the fair market value of the Common Stock shall be deemed to be the
average of the closing bid prices of the Common Stock over the 30-day period
ending five business days prior to the Determination Date, and the fair market
value of the Series Preferred shall be deemed to be such fair market value of
the Common Stock multiplied by the number of shares of Common Stock into which
each share of Series Preferred is then convertible; and

           (C)  If there is no public market for the Common Stock, then fair
market value shall be determined by mutual agreement of the holder of this
Warrant and the Company.

     10.3  Exercise Prior to Expiration.  To the extent this Warrant is not
           ----------------------------
previously exercised as to all of the Shares subject hereto, and if the fair
market value of one share of the Series Preferred is greater than the Warrant
Price then in effect, this Warrant shall be deemed automatically exercised
pursuant to Section 10.2 above (even if not surrendered) immediately before its
expiration.  For purposes of such automatic exercise, the fair market value of
one share of the Series Preferred upon such expiration shall be determined
pursuant to Section 10.2(c).  To the extent this Warrant or any portion thereof
is deemed automatically exercised pursuant to this Section 10.3, the Company
agrees to promptly notify the holder hereof of the number of Shares, if any, the
holder hereof is to receive by reason of such automatic exercise.

     11.   Representations and Warranties.  The Company represents and warrants
           ------------------------------
to the holder of this Warrant as follows:

           (a)  This Warrant has been duly authorized and executed by the
Company and is a valid and binding obligation of the Company enforceable in
accordance with its terms,

                                      -10-
<PAGE>

subject to laws of general application relating to bankruptcy, insolvency and
the relief of debtors and the rules of law or principles at equity governing
specific performance, injunctive relief and other equitable remedies;

          (b)  The Shares have been duly authorized and reserved for issuance by
the Company and, when issued in accordance with the terms hereof, will be
validly issued, fully paid and non-assessable;

          (c)  The rights, preferences, privileges and restrictions granted to
or imposed upon the Series Preferred and the holders thereof are as set forth in
the Charter, and on the Date of Grant, each share of the Series Preferred
represented by this Warrant is convertible into one share of Common Stock;

          (d)  The shares of Common Stock issuable upon conversion of the Shares
have been duly authorized and reserved for issuance by the Company and, when
issued in accordance with the terms of the Charter will be validly issued, fully
paid and nonassessable;

          (e)  The execution and delivery of this Warrant are not, and the
issuance of the Shares upon exercise of this Warrant in accordance with the
terms hereof will not be, inconsistent with the Company's Charter or by-laws, do
not and will not contravene any law, governmental rule or regulation, judgment
or order applicable to the Company, and do not and will not conflict with or
contravene any provision of, or constitute a default under, any indenture,
mortgage, contract or other instrument of which the Company is a party or by
which it is bound or require the consent or approval of, the giving of notice
to, the registration or filing with or the taking of any action in respect of or
by, any Federal, state or local government authority or agency or other person,
except for the filing of notices pursuant to federal and state securities laws,
which filings will be effected by the time required thereby; and

          (f)  There are no actions, suits, audits, investigations or
proceedings pending or, to the knowledge of the Company, threatened against the
Company in any court or before any governmental commission, board or authority
which, if adversely determined, will have a material adverse effect on the
ability of the Company to perform its obligations under this Warrant.

          (g)  The number of shares of Common Stock of the Company outstanding
on the date hereof, on a fully diluted basis (assuming the conversion of all
outstanding convertible securities and the exercise of all outstanding options
and warrants (other than a warrant to purchase Series A Preferred Stock issued
to Dominion Capital Management LLC)), does not exceed 27,718,604 shares.

     12.  Modification and Waiver.  This Warrant and any provision hereof may be
          -----------------------
changed, waived, discharged or terminated only by an instrument in writing
signed by the party against which enforcement of the same is sought.

     13.  Notices.  Any notice, request, communication or other document
          -------
required or permitted to be given or delivered to the holder hereof or the
Company shall be delivered, or

                                      -11-
<PAGE>

shall be sent by certified or registered mail, postage prepaid, to each such
holder at its address as shown on the books of the Company or to the Company at
the address indicated therefor on the signature page of this Warrant.

     14.  Binding Effect on Successors.  This Warrant shall be binding upon any
          ----------------------------
corporation succeeding the Company by merger, consolidation or acquisition of
all or substantially all of the Company's assets, and all of the obligations of
the Company relating to the Series Preferred issuable upon the exercise or
conversion of this Warrant shall survive the exercise, conversion and
termination of this Warrant and all of the covenants and agreements of the
Company shall inure to the benefit of the successors and assigns of the holder
hereof.

     15.  Lost Warrants or Stock Certificates.  The Company covenants to the
          -----------------------------------
holder hereof that, upon receipt of evidence reasonably satisfactory to the
Company of the loss, theft, destruction or mutilation of this Warrant or any
stock certificate and, in the case of any such loss, theft or destruction, upon
receipt of an indemnity reasonably satisfactory to the Company, or in the case
of any such mutilation upon surrender and cancellation of such Warrant or stock
certificate, the Company will make and deliver a new Warrant or stock
certificate, of like tenor, in lieu of the lost, stolen, destroyed or mutilated
Warrant or stock certificate.

     16.  Descriptive Headings.  The descriptive headings of the several
          --------------------
paragraphs of this Warrant are inserted for convenience only and do not
constitute a part of this Warrant.  The language in this Warrant shall be
construed as to its fair meaning without regard to which party drafted this
Warrant.

     17.  Governing Law.  This Warrant shall be construed and enforced in
          -------------
accordance with, and the rights of the parties shall be governed by, the laws of
the State of Washington.

     18.  Survival of Representations.  Warranties and Agreements. All
          ---------------------------
representations and warranties of the Company and the holder hereof contained
herein shall survive the Date of Grant, the exercise or conversion of this
Warrant (or any part hereof) or the termination or expiration of rights
hereunder. All agreements of the Company and the holder hereof contained herein
shall survive indefinitely until, by their respective terms, they are no longer
operative.

     19.  Remedies.  In case any one or more of the covenants and agreements
          --------
contained in this Warrant shall have been breached, the holders hereof (in the
case of a breach by the Company), or the Company (in the case of a breach by a
holder), may proceed to protect and enforce their or its rights either by suit
in equity and/or by action at law, including, but not limited to, an action for
damages as a result of any such breach and/or an action for specific performance
of any such covenant or agreement contained in this Warrant.

     20.  No Impairment of Rights.  The Company will not, by amendment of its
          -----------------------
Charter or through any other means, avoid or seek to avoid the observance or
performance of any of the terms of this Warrant, but will at all times in good
faith assist in the carrying out of all such terms and in the taking of all such
action as may be necessary or appropriate in order to protect the rights of the
holder of this Warrant against impairment.

                                      -12-
<PAGE>

     21.  Severability.  The invalidity or unenforceability of any provision of
          ------------
this Warrant in any jurisdiction shall not affect the validity or enforceability
of such provision in any other jurisdiction, or affect any other provision of
this Warrant, which shall remain in full force and effect.

     22.  Recovery of Litigation Costs.  If any legal action or other proceeding
          ----------------------------
is brought for the enforcement of this Warrant, or because of an alleged
dispute, breach, default, or misrepresentation in connection with any of the
provisions of this Warrant, the successful or prevailing party or parties shall
be entitled to recover reasonable attorneys' fees and other costs incurred in
that action or proceeding, in addition to any other relief to which it or they
may be entitled.

     23.  Entire Agreement; Modification.  This Warrant constitutes the entire
          ------------------------------
agreement between the parties pertaining to the subject matter contained in it
and supersedes all prior and contemporaneous agreements, representations, and
undertakings of the parties, whether oral or written, with respect to such
subject matter.

     24.  "Market Standoff" Agreement.  Each holder of this Warrant hereby
          ---------------------------
agrees that, during the period of duration (up to, but not exceeding, one
hundred eighty (180) days) specified by the Company and an underwriter of Common
Stock or other securities of the Company, following the effective date of a
registration statement of the Company filed under the Securities Act, it shall
not, to the extent requested by the Company and such underwriter, directly or
indirectly sell, offer to sell, contract to sell (including, without limitation,
any short sale), grant any option to purchase or otherwise transfer or dispose
of (other than to donees who agree to be similarly bound) any securities of the
Company held by it at any time during such period except Common Stock included
in such registration;  provided, however, that:

          (a)  such agreement shall be applicable only with respect to the first
such registration statement of the Company which covers Common Stock (or other
securities) to be sold on its behalf to the public in an underwritten offering;
and

          (b)  all officers and directors of the Company, all one-percent
securityholders, and all other persons with registration rights enter into
similar agreements.

          In order to enforce the foregoing covenant, the Company may impose
stop-transfer instructions with respect to the shares of each Holder (and the
shares or securities of every other person subject to the foregoing restriction)
until the end of such period, and each holder of this Warrant agrees that, if so
requested, such holder will execute an agreement in the form provided by the
underwriter containing the terms which are essentially consistent with the
provisions of this Section 24.

          Notwithstanding the foregoing, the obligations described in this
Section 24 shall not apply to a registration relating solely to employee benefit
plans on Form S-i or Form S-S or similar forms which may be promulgated in the
future, or a registration relating solely to an SEC Rule 145 transaction on Form
S-4 or similar forms which may be promulgated in the future. [Signature page
follows]

                                      -13-
<PAGE>

     The Company has caused this Warrant to be duly executed and delivered as of
the Date of Grant specified above.


                                    ONVIA.COM, INC. (f/k/a Megadepot.com, Inc.),
                                    a Washington corporation

                                    By: /s/: Mark Calvert

                                    Title: CFO
                                    Address: 209 1/2 First Avenue South,
                                             Suite 302
                                             Seattle, WA 98104

                                      -14-
<PAGE>

                                  EXHIBIT A-1

                              NOTICE OF EXERCISE

To:  ONVIA.COM, INC. (f/k/a Megadepot.com, Inc.) (the "Company")

     1.   The undersigned hereby:

          [_]  elects to purchase ________ shares of [Series A Preferred Stock]
          [Common Stock] of the Company pursuant to the terms of the attached
          Warrant, and tenders herewith payment of the purchase price of such
          shares in full, or

          [_]  elects to exercise its net issuance rights pursuant to Section
          10.2 of the attached Warrant with respect to _______ Shares of [Series
          A Preferred Stock] [Common Stock].

     2.   Please issue a certificate or certificates representing _________
shares in the name of the undersigned or in such other name or names as are
specified below:


                     _____________________________________
                                    (Name)

                     _____________________________________

                     _____________________________________
                                   (Address)

3.   The undersigned represents that the aforesaid shares are being acquired for
the account of the undersigned for investment and not with a view to, or for
resale in connection with, the distribution thereof and that the undersigned has
no present intention of distributing or reselling such shares, all except as in
compliance with applicable securities laws.

                                             ___________________________________
                                             (Signature)

______________
   (Date)


<PAGE>

                                  EXHIBIT A-2

                              NOTICE OF EXERCISE

To:  ONVIA.COM, INC. (f/k/a Megadepot.com, Inc.) (the "Company")

     1.   Contingent upon and effective immediately prior to the closing (the
"Closing") of the Company's public offering contemplated by the Registration
Statement on Form S___, filed _____, l9__, the undersigned hereby:

          [_]  elects to purchase ______ shares of [Series A Preferred Stock]
               [Common Stock] of the Company (or such lesser number of shares as
               may be sold on behalf of the undersigned at the Closing) pursuant
               to the terms of the attached Warrant, or

          [_]  elects to exercise its net issuance rights pursuant to Section
               10.2 of the attached Warrant with respect to ______ Shares of
               [Series A Preferred Stock] [Common Stock].

     2.   Please deliver to the custodian for the selling shareholders a stock
certificate representing such ______ shares.

     3.   The undersigned has instructed the custodian for the selling
shareholders to deliver to the Company $______ or, if less, the net proceeds due
the undersigned from the sale of shares in the aforesaid public offering.  If
such net proceeds are less than the purchase price for such shares, the
undersigned agrees to deliver the difference to the Company prior to the
Closing.

                                             ___________________________________
                                             (Signature)

______________
   (Date)


<PAGE>

                                   EXHIBIT B

                                    CHARTER