<PAGE>

                                                                     Exhibit 4.5

                                                                       EXHIBIT B

NEITHER THIS WARRANT, NOR THE COMMON STOCK TO BE ISSUED UPON EXERCISE HEREOF,
HAS BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE "ACT"), OR
QUALIFIED UNDER THE APPLICABLE SECURITIES LAWS OF ANY OTHER JURISDICTION (THE
"LAW"), AND THIS WARRANT HAS BEEN, AND THE COMMON STOCK TO BE ISSUED UPON
EXERCISE HEREOF WILL BE, ACQUIRED FOR INVESTMENT AND NOT WITH A VIEW TO, OR FOR
RESALE IN CONNECTION WITH, ANY DISTRIBUTION THEREOF. NO SUCH SALE OR OTHER
DISPOSITION MAY BE MADE WITHOUT AN EFFECTIVE REGISTRATION STATEMENT UNDER THE
ACT AND QUALIFICATION UNDER THE LAW RELATED THERETO OR AN OPINION OF COUNSEL
SATISFACTORY TO THE COMPANY (AS THAT TERM IS DEFINED BELOW) AND ITS COUNSEL,
THAT SAID REGISTRATION AND QUALIFICATION ARE NOT REQUIRED UNDER THE ACT AND LAW,
RESPECTIVELY.

                               TRADEOUT.COM, INC.

February 15, 2000                                                 650,000 Shares
                                                                 of Common Stock

                            Warrant for Common Stock

                  This certifies that Quality King Distributors Incorporated,
whose address is 2060 Ninth Avenue, Ronkonkoma, New York 11779 ("HOLDER") is
entitled to subscribe for and purchase up to six hundred fifty thousand
(650,000) shares of fully paid and nonassessable Common Stock, $0.001 par
value per share ("COMMON Stock"), of TradeOut.com, Inc., a Delaware
corporation (the "COMPANY"), subject to the terms and conditions herewith set
forth. The purchase price of each such share shall be the amount set forth in
Section 1.4 herein. Except as set forth in Sections 7.1 and 11, this Warrant
shall not be assignable, and shall only be exercisable, by Holder.

1.     EXERCISE; PAYMENT

       1.1. EXERCISABILITY. This Warrant, and the right to purchase vested
Common Stock hereunder, shall be exercisable, at any time and from time to time,
commencing on the date of closing of an underwritten initial public offering of
the Common Stock pursuant to an effective registration statement under the
Securities Act of 1933, as amended (the "ACT"), and terminating at 5:00 P.M.,
New York local time on June 30, 2005.

       1.2. PAYMENT. The purchase rights under this Warrant may be exercised by
Holder, in whole or in part, by the surrender of this Warrant at the principal
office of the Company located at 410 Saw Mill River Road, Suite 2065, Ardsley,
New York 10502, and by the payment to the Company, by certified, cashier's or
other check acceptable to the Company, of an amount equal to the aggregate
Warrant Price of the shares being purchased.

       1.3. STOCK CERTIFICATES. In the event of any exercise of the rights to
acquire Common Stock granted under this Warrant, certificates for the shares of
Common Stock so purchased shall be delivered to Holder within a reasonable time
and, unless this Warrant has been fully exercised or has expired, a new Warrant
representing the shares with respect to which this Warrant shall not have been
exercised shall also be issued to Holder within such time.

       1.4. WARRANT PRICE. The purchase price for the shares of Common Stock to
be issued upon exercise of this Warrant shall be $1.00 per share, subject to
adjustment as provided in Section 4 herein (the "WARRANT PRICE").

<PAGE>

       1.5.   VESTING SCHEDULE.

       (a) Subject to the terms and conditions of the Strategic Alliance
Agreement dated as of February ___, 2000 by and between Holder and the Company
(the "AGREEMENT"), this Warrant shall vest in equal quarterly installments of
32,500 shares of Common Stock (each, a "QUARTERLY WARRANT AMOUNT") 31 calendar
days after the last day of each quarter for a period of 20 calendar quarters as
set forth on SCHEDULE A hereto, in each case only if Qualifying Transactions (as
defined in the Agreement) have been completed for such calendar quarter in the
amount listed on SCHEDULE A hereto (the "QUARTERLY GROSS TRANSACTION TARGET").
In the event Qualifying Transactions have been completed in an amount less than
the Quarterly Gross Transaction Target set forth on SCHEDULE A for a particular
quarter, then the Quarterly Warrant Amount for that quarter shall be adjusted in
accordance with the partial vesting schedule set forth on SCHEDULE B hereto.

       (b) The Company may, at any time, without any further action by Holder,
by action of the Board of Directors of the Company, amend this Warrant such that
the vesting schedule set forth in this Section 1.5 shall be accelerated with
respect to all or a portion of the Common Stock.

       (c) Notwithstanding the foregoing provisions of this Section 1.5 this
Warrant shall not become exercisable until Holder has executed a written
agreement to be bound by that certain Right of First Refusal and Co-Sale
Agreement, dated as of October 18, 1999, by and among the Company and the
stockholders of the Company.

2.     REPRESENTATIONS AND WARRANTIES OF HOLDER

            Holder represents and warrants to and covenants with the Company and
each officer, director, and agent of the Company that:

       2.1. Holder has all requisite capacity to enter into the Agreement and to
perform all the obligations required to be performed by Holder thereunder and
hereunder.

       2.2. Holder has such knowledge, skill and experience in business,
financial and investment matters so that Holder is capable of evaluating the
merits and risks of an investment in this Warrant and the Common Stock issuable
hereunder (the "SECURITIES") and has the ability to suffer the total loss of the
investment. To the extent necessary, Holder has retained, at Holder's own
expense, and relied upon, appropriate professional advice regarding the
investment, tax and legal merits and consequences of this Warrant and owning the
Securities. Holder further represents that it has had the opportunity to ask
questions of and receive answers from the Company concerning the terms and
conditions of the Securities, the business of the Company, and to obtain
additional information to such Holder's satisfaction.

       2.3. Holder is an "accredited investor" as defined in Rule 501(a) under
the Act. Holder agrees to furnish any additional information requested to assure
compliance with applicable federal and state securities laws in connection with
the purchase and sale of the Securities.



                                       2
<PAGE>

       2.4. Holder is acquiring the Securities solely for its own account, for
investment purposes, and not with a view to, or for resale in connection with,
any distribution thereof. Holder understands that the Securities have not been
registered under the Act, or any state securities laws by reason of specific
exemptions under the provisions thereof which depend in part upon the investment
intent of Holder and of the other representations made by Holder in this
Warrant. Holder understands that the Company is relying upon the representations
and agreements contained in this Warrant (and any supplemental information) for
the purpose of determining whether this transaction meets the requirements for
such exemptions.

       2.5. Holder acknowledges and agrees that this Warrant and all shares of
Common Stock issued upon exercise hereof shall be stamped or imprinted with a
legend in substantially the following form (in addition to any legend required
by state securities law):

THESE SECURITIES HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED (THE "ACT"), OR QUALIFIED UNDER THE APPLICABLE SECURITIES LAWS OF ANY
OTHER JURISDICTION (THE "LAW"), AND THESE SECURITIES HAVE BEEN ACQUIRED FOR
INVESTMENT AND NOT WITH A VIEW TO, OR FOR RESALE IN CONNECTION WITH, ANY
DISTRIBUTION THEREOF. NO SUCH SALE OR OTHER DISPOSITION MAY BE MADE WITHOUT AN
EFFECTIVE REGISTRATION STATEMENT UNDER THE ACT AND QUALIFICATION UNDER THE LAW
RELATED THERETO OR AN OPINION OF COUNSEL SATISFACTORY TO THE COMPANY AND ITS
COUNSEL, THAT SAID REGISTRATION AND QUALIFICATION ARE NOT REQUIRED UNDER THE ACT
AND LAW, RESPECTIVELY.

3.     STOCK FULLY PAID; RESERVATION OF SHARES

                  The Company covenants and agrees that all securities which may
be issued upon the exercise of the rights represented by this Warrant will, upon
issuance, be fully paid and nonassessable and free from all taxes, liens and
charges with respect to the issuance thereof (excluding taxes based on the
income of Holder). The Company further covenants and agrees that 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 issuance a sufficient
number of shares of its Common Stock or other securities as would be required
upon the full exercise of the rights represented by this Warrant.

4.     ADJUSTMENT

                  The kind of securities purchasable upon the exercise of this
Warrant, the number of shares under this Warrant and the Warrant Price shall be
subject to adjustment from time to time upon the happening of certain events, as
follows:

       4.1. RECLASSIFICATION, CONSOLIDATION OR MERGER. In case of: (i) any
reclassification or change of outstanding securities issuable upon exercise of
this Warrant; (ii) any consolidation or merger of the Company with or into
another corporation (other than a merger with another corporation in which the
Company is a continuing corporation and which does not result in any
reclassification, change or exchange of outstanding securities issuable upon
exercise of this Warrant); or (iii) any sale or transfer to another corporation
of all, or substantially all, of the property of the Company, then, and in each
such event, the Company or such successor or purchasing corporation, as the case
may be, shall execute a new Warrant which will provide that Holder shall have
the right to exercise such new Warrant and purchase upon such exercise, in lieu
of each share of Common Stock theretofore issuable upon exercise of this
Warrant, the kind



                                       3
<PAGE>

of securities, money and property receivable upon such reclassification, change,
consolidation, merger, sale or transfer by a holder of Common Stock issuable
upon exercise of this Warrant had this Warrant been considered exercised
immediately prior to such reclassification, change, consolidation, merger, sale
or transfer. Such new Warrant shall provide for adjustments which shall be as
nearly equivalent as may be practicable to the adjustments provided in this
Section 4 and the provisions of this Section 4 and the provisions of this
Section 4.1 shall similarly apply to successive reclassifications, changes,
consolidations, mergers, sales and transfers.

       4.2. SUBDIVISIONS OR COMBINATION OF SHARES. If the Company at any time
while this Warrant remains outstanding and unexercised, in whole or in part, (i)
shall divide its Common Stock, the Warrant Price shall be proportionately
reduced and the number of shares under this Warrant shall be proportionately
increased; or (ii) shall combine shares of its Common Stock, the Warrant Price
shall be proportionately increased and the number of shares under this Warrant
shall be proportionately reduced.

       4.3. STOCK DIVIDENDS. If the Company, at any time while this Warrant is
outstanding and unexpired, shall pay a dividend payable in, or make any other
distribution to shareholders of, its capital stock (except any distribution
described in Sections 4.1 and 4.2 hereof), then and in each case, this Warrant
shall represent the right to acquire, in addition to the number of shares of the
security receivable upon exercise of this Warrant, and without payment of any
additional consideration therefor, the amount of such additional stock of the
Company which such holder would hold on the date of such exercise had it been
the holder of record of the security receivable upon exercise of this Warrant on
the date hereof and had thereafter, during the period from the date hereof to
and including the date of such exercise, retained such shares and/or all other
additional stock available by it as aforesaid during such period, giving effect
to all adjustments called for during such period by the provisions of this
Section 4.

       4.4. TIME OF ADJUSTMENTS. All adjustments, unless otherwise specified
herein, shall be effective as of the earlier of:

              4.4.1. the date of issuance of the security causing the
adjustment;

              4.4.2. the effective date of a division or combination of shares;

              4.4.3. the record date of any action of holders of the Company's
capital stock of any class taken for the purpose of dividing or combining shares
or entitling shareholders to receive a distribution or dividends payable in the
Company's capital stock.

       4.5. NOTICE OF ADJUSTMENTS. In each case of an adjustment the Company, at
its expense, shall cause the Chief Financial Officer (or other such similar
officer) of the Company to compute such adjustments and prepare a certificate
setting forth such adjustments and showing in detail the facts upon which such
adjustment is based. The Company shall promptly mail a copy of each such
certificate to Holder pursuant to Section 15 hereof.



                                       4
<PAGE>

5.       FRACTIONAL SHARES

                  No fractional share of Common Stock will be issued in
connection with any exercise hereof, but in lieu of a fractional share upon
complete exercise hereof, Holder may purchase a whole share at the then
effective Warrant Price.

6.       SHAREHOLDER RIGHTS

                  Holder shall not, solely by virtue hereof, be entitled to any
rights of a shareholder of the Company. Holder shall have all rights of a
shareholder with respect to securities purchased upon exercise hereof at the
time the exercise price for such securities is delivered pursuant to Section l
hereof and this Warrant is surrendered.

7.       RESTRICTIONS ON TRANSFER

       7.1. TRANSFER OF WARRANT. This Warrant shall not be transferable by
Holder except pursuant to prior written consent of the Company, which consent
shall not be unreasonably withheld or delayed, and provided that such transferee
executes a written agreement to be bound by the provisions of this Warrant.

       7.2. SECURITIES LAWS RESTRICTIONS. Holder, by acceptance hereof, agrees
that, absent an effective registration statement under the Act covering the
disposition of Common Stock issued or issuable upon exercise hereof, Holder will
not sell or transfer any or all of such Common Stock, without first providing
the Company with an opinion of counsel reasonably acceptable to the Company and
its counsel to the effect that such sale or transfer will be exempt from the
registration requirements of the Act, and Holder consents to the Company making
a notation on its records in order to implement such restriction on
transferability.

8.       "MARKET STAND-OFF" AGREEMENT

                  You hereby agree that, during the period specified by the
Company and any underwriter of Common Stock or other securities of the Company
following the effective date of a registration statement of the Company filed
under the Act, you will 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 you at any time during such period
except Common Stock included in such registration. To enforce the foregoing
covenant, the Company may impose stop-transfer instructions with respect to the
shares of Common Stock issued or issuable upon exercise of this Warrant held by
you until the end of such period. In addition, the foregoing covenant may be
enforced by the underwriters who are parties with the Company to an underwriting
agreement under which such public offering is being undertaken.

9.       LOSS OR MUTILATION

                  Upon receipt by the Company of evidence satisfactory to it of
the ownership of, and the loss, theft, destruction or mutilation of, this
Warrant and (in the case of loss, theft or



                                       5
<PAGE>

destruction) of indemnity satisfactory to it, and (in the case of mutilation)
upon surrender and cancellation hereof, the Company will execute and deliver in
lieu hereof a new Warrant.

10.      GOVERNING LAW

                  The internal laws of the State of Delaware (irrespective of
its choice of law principles) shall govern the validity of this Warrant, the
construction of its terms, and the interpretation and enforcement of the rights
and duties of the parties hereto.

11.      BINDING UPON SUCCESSORS AND ASSIGNS

                  Subject to, and unless otherwise provided in, this Warrant,
each and all of the covenants, terms, provisions, and agreements contained
herein shall be binding upon, and inure to the benefit of the permitted
successors, executors, heirs, representatives, administrators and assigns of the
parties hereto. Holder shall not assign this Warrant or any rights or
obligations hereunder without the prior written consent of the Company, which
consent shall not be unreasonably withheld. For purposes of this Section 11, the
sale of all or substantially all of Holder's assets or capital stock shall
constitute an assignment.

12.      SEVERABILITY

                  If any provision of this Warrant, or the application hereof,
shall for any reason and to any extent, be invalid or unenforceable, the
remainder of this Warrant and application of such provisions to other persons or
circumstances shall be interpreted so as best to reasonably effect the intent of
the parties hereto. The parties further agree to replace such void or
unenforceable provisions of this Warrant with valid or enforceable provisions
which will achieve, to the extent possible, the economic, business and other
purposes of the void or unenforceable provisions.

13.      AMENDMENT

                  This Warrant may be amended upon the written consent of the
Company and Holder.

14.      NO WAIVER

                  The failure of any party to enforce any of the provisions
hereof shall not be construed to be a waiver of the right of such party
thereafter to enforce such provisions.

15.      NOTICES

                  Whenever any party hereto desires or is required to give any
notice, demand, or request with respect to this Warrant, each such communication
shall be in writing and shall be effective only if it is delivered by personal
service or mailed, United States certified mail, postage prepaid, return receipt
requested, addressed as follows:

         Company: Address set forth in Section 1 hereof
                  Attn: Chief Executive Officer



                                       6
<PAGE>

         Holder:  Address as set forth in Section 1 hereof
                  Attn: [                   ]

Such communications shall be effective when they are received by the addresses
thereof; but if sent by certified mail in the manner set forth above, they shall
be effective five (5) days after being deposited in the United States mail. Any
party may change its address for such communications by giving notice thereof to
the other party in conformity with this Section.

16.      CONSTRUCTION OF AGREEMENT

                  A reference in this Warrant to any Section shall include a
reference to every Section the number of which begins with the number of the
Section to which reference is specifically made. The titles and headings herein
are for reference purposes only and shall not in any manner limit the
construction of this Warrant which shall be considered as a whole.

17.      NO ENDORSEMENT

                  Holder understands that no federal or state securities
administrator has made any finding or determination relating to the fairness of
investment in the Company or purchase of the Common Stock hereunder and that no
federal or state securities administrator has recommended or endorsed the
offering of securities by the Company hereunder.

18.      PRONOUNS

                  All pronouns and any variations thereof shall be deemed to
refer to the masculine, feminine or neuter, singular or plural, as the identity
of the person, persons, entity or entities may require.

19.      FURTHER ASSISTANCE

                  Each party agrees to cooperate fully with the other parties
and to execute such further instruments, documents and agreements and to give
such further written assurances, as may be reasonably requested by any other
party to better evidence and reflect the transactions described herein and
contemplated hereby, and to carry into effect the intents and purposes of this
Warrant.

                                       TradeOut.com, Inc.

                                       By: /s/ James Mooney
                                          --------------------------
                                          Title: CFO

ACCEPTED THIS ___ DAY OF FEBRUARY 2000



                                       7
<PAGE>

QUALITY KING DISTRIBUTORS INCORPORATED


By:      /s/ Glenn Nussdorf
   ______________________________________
      Name:  Glenn Nussdorf
      Title: President & CEO


                                       8
<PAGE>



                            FORM OF WARRANT EXERCISE
                   (TO BE SIGNED ONLY ON EXERCISE OF WARRANT)


TO _______________________

                  The undersigned, the holder of the within Warrant, hereby
irrevocably elects to exercise this Warrant for, and to purchase thereunder,
______ shares of Common Stock of TradeOut.com, Inc., a Delaware corporation, and
herewith makes payment of $__________ therefor, and requests that the
certificates for such shares be issued in the name of, and delivered to
_____________, whose address is __________________________.

Dated:


                                  _____________________________________________
                                  (Signature must conform to name of holder as
                                       specified on the face of the Warrant)


                                  _____________________________________________
                                                   (Address)



                                  Tax Identification Number: __________________


<PAGE>


SCHEDULE A

                         SCHEDULE OF VESTING OF WARRANT

<TABLE>
<CAPTION>
---------------------------------------- -------------------------------------- --------------------------------------
PERIOD                                   QUARTERLY GROSS                        QUARTERLY WARRANT AMOUNT
(Q = CALENDAR QUARTER)                   TRANSACTION TARGET
---------------------------------------- -------------------------------------- --------------------------------------
<S>                                      <C>                                    <C>
Q1 2000                                  $5.4 million                           32,500
---------------------------------------- -------------------------------------- --------------------------------------
Q2 2000                                  $10.8 million                          32,500
---------------------------------------- -------------------------------------- --------------------------------------
Q3 2000                                  $18 million                            32,500
---------------------------------------- -------------------------------------- --------------------------------------
Q4 2000                                  $25.5 million                          32,500
---------------------------------------- -------------------------------------- --------------------------------------
Q1 2001                                  $19.5 million                          32,500
---------------------------------------- -------------------------------------- --------------------------------------
Q2 2001                                  $19.5 million                          32,500
---------------------------------------- -------------------------------------- --------------------------------------
Q3 2001                                  $19.5 million                          32,500
---------------------------------------- -------------------------------------- --------------------------------------
Q4 2001                                  $19.5 million                          32,500
---------------------------------------- -------------------------------------- --------------------------------------
Q1 2002                                  $25.5 million                          32,500
---------------------------------------- -------------------------------------- --------------------------------------
Q2 2002                                  $25.5 million                          32,500
---------------------------------------- -------------------------------------- --------------------------------------
Q3 2002                                  $25.5 million                          32,500
---------------------------------------- -------------------------------------- --------------------------------------
Q4 2002                                  $25.5 million                          32,500
---------------------------------------- -------------------------------------- --------------------------------------
Q1 2003                                  $33 million                            32,500
---------------------------------------- -------------------------------------- --------------------------------------
Q2 2003                                  $33 million                            32,500
---------------------------------------- -------------------------------------- --------------------------------------
Q3 2003                                  $33 million                            32,500
---------------------------------------- -------------------------------------- --------------------------------------
Q4 2003                                  $33 million                            32,500
---------------------------------------- -------------------------------------- --------------------------------------
Q1 2004                                  $42 million                            32,500
---------------------------------------- -------------------------------------- --------------------------------------
Q2 2004                                  $42 million                            32,500
---------------------------------------- -------------------------------------- --------------------------------------
Q3 2004                                  $42 million                            32,500
---------------------------------------- -------------------------------------- --------------------------------------
Q4 2004                                  $42 million                            32,500
---------------------------------------- -------------------------------------- --------------------------------------
</TABLE>

<PAGE>


SCHEDULE B

PARTIAL VESTING SCHEDULE:

If Holder does not achieve the Quarterly Gross Transaction Target in a
particular quarter, the Quarterly Warrant Amount for that quarter shall be
adjusted as follows:

       % of Quarterly Gross               % of Quarterly Warrant
    TRANSACTION TARGET ACHIEVED                 AMOUNT VESTED
         0.01% - 54.99%                         0% (0 shares)

        55.00% - 79.99%                      50% (16,250 shares)
        80.00% - 99.99%                      70% (22,750 shares)
          100% and above                    100% (32,500 shares)