<PAGE>   1



                                                                   Exhibit 10.90


                            STOCK PURCHASE AGREEMENT

        THIS STOCK PURCHASE AGREEMENT (this "Agreement"), dated as of September
20, 2001, is by and between Royal Investments Corp., a Delaware corporation with
offices at 380 Tucker Drive, Worthington, Ohio 43085 (the "Purchaser"), and
CROWN NORTHCORP, INC., a Delaware corporation with offices at 1251 Dublin Road,
Columbus, Ohio 43215 (the "Seller").

                             BACKGROUND INFORMATION
                             ----------------------

        WHEREAS, the Purchaser desires to purchase from the Seller, and the
Seller desires to sell to the Purchaser, one share of the Series GG Convertible
Preferred Stock, par value $.01 per share, of the Seller (the "Seller Preferred
Stock"), on the terms and conditions set forth herein;

        NOW, THEREFORE, in consideration of the foregoing and for other good and
valuable consideration, the adequacy, sufficiency, and receipt of which are
hereby acknowledged, the parties hereto agree as follows:

                             STATEMENT OF AGREEMENT
                             ----------------------

                                    ARTICLE I
                                    ---------
                              THE PURCHASE AND SALE
                              ---------------------

         SECTION 1.1. TERMS OF THE PURCHASE AND SALE. On the basis of and in
reliance upon the representations and warranties set forth in Articles II and
III, and subject to the terms and conditions set forth herein:

         (a) The Seller shall issue at the Closing (as hereinafter defined) to
the Purchaser a certificate registered in the name of the Purchaser for one
share (the "Closing Share") of Seller Preferred Stock.

         (b) As consideration for the Closing Share, Seller and Purchaser
understand and agree that Seller is issuing the Closing Share with a stated
value of $140,000 in full and complete satisfaction of any obligation Seller has
or may have to Purchaser arising out of Purchaser's cash advances to Seller to
the date hereof in the aggregate amount of $140,000.

         SECTION 1.2. THE CLOSING. The closing of the transaction contemplated
by Section 1.1 (the "Closing") shall take place at such place and time on or
before September 20, 2001 as the Purchaser and the Seller agree.


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         SECTION 1.3. CONDITIONS TO THE OBLIGATION OF THE PURCHASER TO
CONSUMMATE THE TRANSACTIONS TO BE CONSUMMATED HEREUNDER AT THE CLOSING. The
obligations of the Purchaser to consummate the transactions to be consummated
hereunder at the Closing are subject to the following conditions (unless waived
by the Purchaser in its discretion):

         (a) ACCURACY OF REPRESENTATIONS AND COMPLIANCE WITH CONDITIONS. All
representations and warranties of the Seller contained in Article II of this
Agreement shall be true and correct as of the Closing; as of the Closing the
Seller shall have performed and complied with all covenants and agreements and
satisfied all conditions required to be performed and complied with by the
Seller at or before such time by this Agreement; and the Purchaser shall have
received a certificate of the Seller, dated the Closing Date, to that effect,
substantially in the form of Exhibit A.

         (b) OTHER CLOSING DOCUMENTS. The Seller shall have delivered to the
Purchaser on or prior to the Closing such other documents as the Purchaser may
reasonably request in order to enable the Purchaser to determine whether the
conditions to its obligations under this Agreement have been met and otherwise
to carry out the provisions of this Agreement.

         SECTION 1.4. CONDITIONS TO THE OBLIGATION OF THE SELLER TO CONSUMMATE
THE TRANSACTIONS TO BE CONSUMMATED HEREUNDER AT THE CLOSING. The obligations of
the Seller to consummate the transactions to be consummated hereunder at the
Closing are subject to the following conditions (unless waived by the Seller in
its discretion):

         (a) ACCURACY OF REPRESENTATIONS AND COMPLIANCE WITH CONDITIONS. All
representations and warranties of the Purchaser contained in Article III of this
Agreement shall be true and correct as of the Closing; as of the Closing the
Purchaser shall have performed and complied with all covenants and agreements
and satisfied all conditions required to be performed and complied with by the
Purchaser at or before such time by this Agreement; and the Seller shall have
received a certificate executed by Authorized Signatories of the Purchaser,
dated the date of the Closing, to that effect, substantially in the form of
Exhibit B.

         (b) OTHER CLOSING DOCUMENTS. The Purchaser shall have delivered to the
Seller at or prior to the Closing such other documents, including, without
limitation, an Investors Questionnaire, as the Seller may reasonably request in
order to enable the Seller to determine whether the conditions to its
obligations under this Agreement have been met and otherwise to carry out the
provisions of this Agreement.


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                                   ARTICLE II
                                   ----------
                  REPRESENTATIONS AND WARRANTIES OF THE SELLER
                  --------------------------------------------

         SECTION 2.1. REPRESENTATIONS AND WARRANTIES. The Seller represents and
warrants to the Purchaser as of the Closing as follows:

         (a) ORGANIZATION AND QUALIFICATION. The Seller is a corporation duly
organized, validly existing, and in good standing under the laws of its
jurisdiction of incorporation or organization, with all requisite power and
authority, and all necessary consents, authorizations, approvals, orders,
licenses, certificates, and permits of and from, and declarations and filings
with, all federal, state, local, and other governmental authorities and all
courts and other tribunals, to own, lease, license, and use its properties and
assets and to carry on the business in which it is now engaged, except for such
consents, authorizations, approvals, orders, licenses, certificates, permits,
declarations, and filings, the absence of which, individually or in the
aggregate, could not reasonably be expected to have a material and adverse
effect upon the business, financial condition, or results of operation of the
Seller taken as a whole (a "Material Adverse Effect"). The Seller is duly
qualified to transact the business in which it is engaged and is in good
standing as a foreign corporation in every jurisdiction in which its ownership,
leasing, licensing, or use of property or assets or the conduct of its business
makes such qualification necessary, except where the absence of such
qualification or good standing could not reasonably be expected to have a
Material Adverse Effect.

         (b) CAPITALIZATION. The authorized capital stock of the Seller consists
of (i) 30,000,000 shares of Seller Common Stock, of which 11,431,788 shares are
outstanding as of the date hereof (excluding the Closing Shares), and (ii)
1,000,000 shares of Preferred Stock, par value $.01 per share ("Preferred
Stock"), of which four shares (after accounting for another issuance of
Preferred Stock pursuant to an agreement of even dated herewith) are outstanding
as of the date hereof. Each of such outstanding shares of Seller Common Stock is
duly authorized, validly issued, fully paid, and nonassessable, and was not
issued in violation of any applicable law or of any preemptive right of
stockholders. Except for this Agreement and as set forth on Schedule 2.1(b),
there is no commitment, plan, or arrangement to issue, and no outstanding
option, warrant, or other right calling for the issuance of, any share of
capital stock of the Seller or any security or other instrument convertible
into, exercisable for, or exchangeable for capital stock of the Seller. Except
as set forth on Schedule 2.1(b), there is outstanding no security or other
instrument convertible into or exchangeable for capital stock of the Seller or
of any Subsidiary. As used herein, "Knowledge of the Seller" means the actual
knowledge of any one or more of Ronald E. Roark or Stephen W. Brown, assuming
that each possesses the actual knowledge that an officer or director with their
responsibilities would possess after reasonable inquiry into the applicable
matter.

          (c) AUTHORITY TO SELL. The Seller has all requisite power and
authority to execute, deliver, and perform this Agreement. All necessary
corporate proceedings of the Seller have been duly taken to authorize the
execution, delivery, and performance of this Agreement. This Agreement has been
duly authorized, executed, and delivered by the Seller, constitutes the legal,
valid, and binding obligation of the Seller, and is enforceable against it in
accordance


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with its terms. No consent, authorization, approval, order, license,
certificate, or permit of or from, or declaration or filing with, any federal,
state, local, or other governmental authority or any court or other tribunal is
required by the Seller for the execution, delivery, or performance of this
Agreement. No consent of any party to any contract, agreement, instrument,
lease, license, arrangement, or understanding to which the Seller, or to which
it or any of its businesses, properties, or assets are subject, is required for
the execution, delivery, or performance of this Agreement; and the execution,
delivery, and performance of this Agreement will not violate, result in a breach
of, conflict with, or (with or without the giving of notice or the passage of
time or both) entitle any party to terminate or call a default under, entitle
any party to rights and privileges that such party was not receiving or entitled
to receive immediately before this Agreement was executed under, or create any
obligation on the part of the Seller that it was not paying or obligated to pay
immediately before this Agreement was executed under, any term of any such
contract, agreement, instrument, lease, license, arrangement, or understanding,
or violate or result in a breach of any term of the certificate of incorporation
(or other charter or organizational document) or by-laws (or other governing
document) of the Seller, or (if each of the conditions precedent set forth
herein or in a schedule hereto are satisfied) violate, result in a breach of, or
conflict with any law, rule, regulation, order, judgment, or decree binding on
the Seller or to which it or any of its businesses, properties, or assets are
subject. Upon its issuance pursuant hereto, the Closing Share will be validly
authorized, validly issued, fully paid, and nonassessable and will not have been
issued in violation of any preemptive right of stockholders, and the Purchaser
will then have good title to the Closing Share free and clear of all liens,
security interests, pledges, charges, encumbrances, stockholders' agreements,
and voting trusts.

         (d) DISCLOSURE. Neither this Agreement nor any other written document,
description, certificate, or statement furnished to the Purchaser by or on
behalf of the Seller pursuant hereto or thereto, contains or will contain any
untrue statement of a material fact, or omits or will omit to state a material
fact, necessary to make the statements contained herein and therein not
misleading in light of the circumstances under which they have been or will be
made.

         (e) BROKERAGE FEES. The Seller has not created any liability of any
Person for any brokerage or finders fee in connection with the transactions
contemplated by this Agreement.

                                   ARTICLE III
                                   -----------
                 REPRESENTATIONS AND WARRANTIES OF THE PURCHASER
                 -----------------------------------------------

         SECTION 3.1. REPRESENTATIONS AND WARRANTIES. The Purchaser represents
and warrants to the Seller as of the Closing as follows:

         (a) ORGANIZATION. The Purchaser is a limited liability company duly
organized, validly existing, and in good standing under the laws of the State of
Delaware, with all requisite power and authority to own, lease, license, and use
its properties and assets and to carry on the business in which it is now
engaged and to own securities issued by the Seller as herein contemplated. The
Purchaser is duly qualified to do business in the State of Delaware.


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         (b) AUTHORITY TO BUY. The Purchaser has all requisite power and
authority to execute, deliver, and perform this Agreement. All necessary
proceedings of the Purchaser have been duly taken to authorize the execution,
delivery, and performance of this Agreement by the Purchaser. This Agreement has
been duly authorized, executed, and delivered by the Purchaser, is the legal,
valid, and binding obligation of the Purchaser, and is enforceable against the
Purchaser in accordance with its terms.

         (c) NON-DISTRIBUTIVE INTENT. The Purchaser is an "accredited investor"
(as defined in Rule 501(a) under the Securities Act of 1933, as amended (the
"Securities Act")). The Purchaser is acquiring the securities to be acquired by
it at the Closing for its own account (and not for the account of others) for
investment and not with a view to the resale or other distribution thereof. The
Purchaser will not sell or otherwise dispose of such securities (whether
pursuant to a liquidating dividend or otherwise) without registration under the
Securities Act or an exemption therefrom, and the certificate or certificates
representing such securities may contain a legend to the foregoing effect and
all legends necessary or desirable, in the judgment of the Purchaser, pursuant
to any applicable state securities law, rule, or regulation. The Purchaser
understands that it may not sell or otherwise dispose of such Shares (except to
another accredited investor in accordance with the Securities Act) in the
absence of either a registration statement under the Securities Act or an
exemption from the registration provisions of the Securities Act.

         (d) INVESTMENT COMPANY. The Purchaser is not subject to regulation as
an investment company under the Investment Company Act of 1940, as amended.

         (e) BROKER FEES. Neither the Purchaser nor any of its subsidiaries or
parents has created any liability of any Person for any brokerage or finders fee
in connection with the transactions contemplated by this Agreement.


                                   ARTICLE IV
                                   ----------
                             COVENANTS OF THE SELLER
                             -----------------------

         The Seller covenants to the Purchaser as follows:

         SECTION 4.1. FURNISH FUTURE INFORMATION. After the Closing, the Seller
shall deliver to the Purchaser the following so long as the Purchaser own the
Closing Share:

         (a) within 45 days after the end of each of the first three quarterly
fiscal periods in each fiscal year of the Seller, a consolidated balance sheet
of the Seller and its consolidated subsidiaries as at the end of such period,
and a consolidated statement of income, consolidated statement of retained
earnings, and consolidated statement of cash flows of Seller and its
consolidated subsidiaries for such period, in each case prepared from the books
and records of the Seller and its consolidated subsidiaries in accordance with
generally accepted accounting principles ("GAAP") consistently applied
throughout the periods involved except as permitted


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by GAAP or, with respect to financial statement footnotes, by the applicable
rules and regulations of the Commission, setting forth in each case in
comparative form the figures for the corresponding period of the previous fiscal
year, all in reasonable detail, subject to changes resulting from year-end audit
adjustments;

         (b) within 90 days after the end of each fiscal year of the Seller, a
consolidated balance sheet of the Seller and its consolidated subsidiaries as at
the end of such year, and a consolidated statement of income, consolidated
statement of retained earnings, and consolidated statement of cash flows of the
Seller and its consolidated subsidiaries for such year, setting forth in each
case in comparative form the figures for the previous fiscal year, all in
reasonable detail, such consolidated financial statements to be audited by and
to be accompanied by an opinion of the Seller's independent certified public
accountants of recognized national standing, which opinion shall state that such
consolidated financial statements have been prepared in accordance with
generally accepted accounting principles consistently applied and that the audit
by such accountants in connection with such consolidated financial statements
has been made in accordance with generally accepted auditing standards;

         (c) promptly upon their becoming available, copies of all financial
statements, reports, notices, and proxy statements sent by the Seller to its
stockholders, all regular and periodic reports filed by the Seller with any
securities exchange or with the Commission, and all press releases; and

         (d) with reasonable promptness, such other material and public
information and data with respect to the Seller or any of its Subsidiaries as
from time to time may be requested by the Purchaser.

         SECTION 4.2. REASONABLE BEST EFFORTS. Each of the Seller and the
Purchaser agrees to cooperate and to use its reasonable best efforts to cause
the conditions precedent to the Closing to be satisfied in a timely manner.

         SECTION 4.3. RESERVATION OF AUTHORIZED SHARES. For so long as the
Purchaser holds the Seller Preferred Stock, Seller shall continuously hold in
reserve sufficient shares of Seller Common Stock to perform its conversion
obligations under the terms of the Seller Preferred Stock.

                                    ARTICLE V
                                    ---------
                           COVENANTS OF THE PURCHASER
                           --------------------------

         The Purchaser covenants to the Seller as follows:

         SECTION 5.1. COMPLIANCE WITH SECURITIES LAWS. The Purchaser agrees to
make all filings required to be made by it under the Securities Exchange Act of
1934 (the "Exchange Act")with respect to its holdings of securities issued by
the Seller on a timely basis.



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                                   ARTICLE VII
                                   -----------
                                  MISCELLANEOUS
                                  -------------

         SECTION 7.1. FURTHER ACTIONS. At any time and from time to time, each
party agrees, at its or his expense, to take such actions and to execute and
deliver such documents as may be reasonably necessary to effectuate the purposes
of this Agreement.

         SECTION 7.2. AVAILABILITY OF EQUITABLE REMEDIES. Since a breach of the
provisions of this Agreement may not adequately be compensated by money damages,
any party shall be entitled, in addition to any other right or remedy available
to it, to an injunction restraining such breach or a threatened breach and to
specific performance of any such provision of this Agreement, and in either case
no bond or other security shall be required in connection therewith, and the
parties hereby consent to the issuance of such an injunction and to the ordering
of specific performance.

         SECTION 7.3. SURVIVAL. The covenants, agreements, representations, and
warranties contained in or made pursuant to this Agreement shall survive the
Closing and any delivery of any purchase price by the Purchaser, irrespective of
any investigation made by or on behalf of any party for a period of two (2)
calendar years after such Closing.

         SECTION 7.4. MODIFICATION. This Agreement and the Exhibits and
Schedules hereto, set forth the entire understanding of the parties with respect
to the subject matter hereof, supersede all existing agreements among them
concerning such subject matter, and may be modified only by a written instrument
duly executed by each party (except as otherwise provided in Section 7.5).

         SECTION 7.5. NOTICES. Any notice or other communication required or
permitted to be given hereunder shall be in writing and shall be mailed by
certified mail, return receipt requested (in which case it shall be deemed to be
given five days after mailing) or by Federal Express, Express Mail, or similar
overnight delivery or courier service (in which case it will be deemed to be
given upon actual receipt by the recipient) or delivered (in person or by
telecopy, telex, or similar telecommunications equipment) against receipt to the
party to whom it is to be given at the address of such party set forth below (or
to such other address as the party shall have furnished in writing in accordance
with the provisions of this Section 7.5):

         If to the Purchaser:

                  Royal Investments Corp.
                  380 Tucker Drive
                  Worthington, Ohio 43015
                  Attn.: Ronald E. Roark, President
                  Fax:   614/854-9724


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         If to the Seller:

                  Crown NorthCorp, Inc.
                  1251 Dublin Road
                  Columbus, Ohio 43215
                  Attn:  Stephen W. Brown
                  Fax:   614/488-9780

         SECTION 7.6. WAIVER. Any waiver by any party of a breach of any term of
this Agreement shall not operate as or be construed to be a waiver of any other
breach of that term or of any breach of any other term of this Agreement. The
failure of a party to insist upon strict adherence to any term of this Agreement
on one or more occasions will not be considered a waiver or deprive that party
of the right thereafter to insist upon strict adherence to that term or any
other term of this Agreement. Any waiver must be in writing.

         SECTION 7.7. BINDING EFFECT. The provisions of this Agreement shall be
binding upon and inure to the benefit of the Seller, the Purchaser, and their
respective successors and assigns.

         SECTION 7.8. NO THIRD PARTY BENEFICIARIES. This Agreement does not
create, and shall not be construed as creating, any rights enforceable by any
person not a party to this Agreement (except as provided in Section 7.7).

         SECTION 7.9. SEPARABILITY. If any provision of this Agreement is
invalid, illegal, or unenforceable, the balance of this Agreement shall remain
in effect, and if any provision is inapplicable to any person or circumstance,
it shall nevertheless remain applicable to all other persons and circumstances.

         SECTION 7.10. HEADINGS. The headings in this Agreement are solely for
convenience of reference and shall be given no effect in the construction or
interpretation of this Agreement.

         SECTION 7.11. COUNTERPARTS; GOVERNING LAW. This Agreement may be
executed in any number of counterparts, each of which shall be deemed an
original, but all of which together shall constitute one and the same
instrument. It shall be governed by and construed in accordance with the laws of
the State of Delaware, without giving effect to conflict of laws.

         SECTION 7.12. ASSIGNMENTS. This Agreement may be assigned by operation
of law without the consent of any party hereto. This Agreement may be assigned
by the Purchaser to its affiliate without the consent of the Seller. This
Agreement may not otherwise be assigned by any party hereto without the prior
written consent of the other party hereto, which consent



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shall not be unreasonably delayed or withheld.

         IN WITNESS WHEREOF, the parties have duly executed this Agreement as of
the date first written above.


                             ROYAL INVESTMENTS CORP.



                             By:    /s/ Ronald E. Roark
                                 ----------------------------------------
                                      Name:   Ronald E. Roark
                                      Title:  President


                             CROWN NORTHCORP, INC.




                             By:   /s/ Stephen W. Brown
                                 ----------------------------------------
                                      Name:   Stephen W. Brown
                                      Title:  Secretary














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                                    EXHIBIT A

                         SELLER'S OFFICER'S CERTIFICATE

         Capitalized terms used herein but not otherwise defined herein shall
have the meanings ascribed thereto in that certain Stock Purchase Agreement,
dated as of September 20, 2001, between and among Royal Investments Corp. and
Crown NorthCorp, Inc. (the "Stock Purchase Agreement").

         The undersigned, being the Secretary of CROWN NORTHCORP, INC., a
Delaware corporation (the "Seller"), DOES HEREBY CERTIFY, in the name and on
behalf of the Company, as follows:

         1. All representations and warranties of the Seller contained in
Article II of the Stock Purchase Agreement are true and correct as of the date
hereof.

         2. As of the date hereof, the Seller has performed and complied with
all covenants and agreements, and satisfied all conditions required to be
performed and complied with, by the Seller at or before the date hereof by the
Stock Purchase Agreement.

         IN WITNESS WHEREOF, the undersigned has set his hand hereunto, in the
name and on behalf of the Company, as of September 20, 2001.


                                       CROWN NORTHCORP, INC.


                                       By:
                                          -------------------------------------
                                         Stephen W. Brown, Secretary



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                                    EXHIBIT B
                        PURCHASER'S OFFICER'S CERTIFICATE

         Capitalized terms used herein but not otherwise defined herein shall
have the meanings ascribed thereto in that certain Stock Purchase Agreement,
dated as of September 20, 2001, between and among Royal Investments Corp. and
Crown NorthCorp, Inc. (the "Stock Purchase Agreement").

         The undersigned, being the President of Royal Investments Corp., a
corporation organized under the laws of the State of Delaware, (the
"Purchaser"), DOES HEREBY CERTIFY, in the name and on behalf of the Purchaser,
as follows:

         1. As of the date hereof, all representations and warranties of the
Purchaser contained in Article III of the Stock Purchase Agreement are true and
correct as of the date hereof.

         2. As of the date hereof, the Purchaser has performed and complied with
all covenants and agreements, and satisfied all conditions required to be
performed and complied with, by the Purchaser at or before the date hereof by
the Stock Purchase Agreement.

         3. The Purchaser is an "accredited investor," as defined in Rule 501(a)
under the Securities Act.

         4. The Purchaser is purchasing the Closing Share for its own account,
for investment purposes only, and without a view toward the resale or
distribution thereof.

         5. The Seller has made available to the Purchaser a reasonable time
before the Closing the opportunity to ask questions of and receive answers
concerning the Seller and the terms and conditions of the transaction to be
consummated at the Closing.






<PAGE>   12



         IN WITNESS WHEREOF, the undersigned has set his hand hereunto, in the
name and on behalf of the Company, as of September 20, 2001.


                                  ROYAL INVESTMENTS CORP.




                                  By:
                                     -----------------------------------------
                                           Name:
                                           Title:






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