<PAGE>
 
                                                               EXHIBIT 10.24(ii)




                             SPP PURCHASE AGREEMENT



                                  BY AND AMONG



              WESTMARK REAL ESTATE ACQUISITION PARTNERSHIP, L.P.,

                     CB COMMERCIAL REAL ESTATE GROUP, INC.

                                      AND


                         ______________________________



                                August 15, 1997
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                             SPP PURCHASE AGREEMENT


     THIS SPP PURCHASE AGREEMENT (the "Agreement") is made and entered into as
of the 15th day of August, 1997 by and among WESTMARK REAL ESTATE ACQUISITION
PARTNERSHIP, L.P., a limited partnership organized under the laws of Delaware
("Purchaser"), CB COMMERCIAL REAL ESTATE GROUP, INC., a Delaware corporation
("CBC"), and _____________, an individual ("Owner").


                                R E C I T A L S


     A.   Pursuant to the Purchase Agreement, dated May 15, 1995 by and among
Purchaser, CBC, the Controlling Westmark Owners and the Individual Westmark
Owners (the "1995 Purchase Agreement"), Purchaser acquired all of the voting and
ownership interests in Westmark Realty Advisors L.L.C., a Delaware limited
liability company ("Westmark"), from the Controlling Westmark Owners and the
Individual Westmark Owners (as defined in the 1995 Purchase Agreement).

     B.   Purchaser currently is obligated to pay to Owner, the other
Controlling Westmark Owners and the Individual Westmark Owners the Supplemental
Purchase Price under the terms and conditions set forth in the 1995 Purchase
Agreement (the "Supplemental Purchase Price").

     C.   Purchaser desires to purchase from Owner, and Owner desires to sell to
Purchaser, all of Purchasers' right, title and interest in and to the
Supplemental Purchase Price.

     D.   The parties hereto desire to modify certain of the rights and
obligations of the parties established by the 1995 Purchase Agreement and the
ancillary agreements entered into in connection therewith.

     NOW, THEREFORE, in consideration of the foregoing and the representations,
warranties, agreements and covenants herein contained, and for other
consideration, the receipt and adequacy of which are hereby acknowledged, the
parties hereto agree as follows:


                                   ARTICLE 1

                                  TRANSACTIONS
                                  ------------

     1.1  Payment in Satisfaction of Supplemental Purchase Price.  Subject to
          ------------------------------------------------------             
the conditions set forth in Section 1.5, Purchaser hereby agrees to pay to Owner
the SPP Payment as set forth in Schedule 1.1 on the Payment Date set forth on
such Schedule by cashier's check payable to Owner, and Owner agrees to accept
such payment, in full and complete satisfaction of any and all obligations of
Purchaser or CBC (whether

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presently accrued or to accrue hereafter) to pay the Supplemental Purchase Price
under the 1995 Purchase Agreement.

     1.2  Changes to Transaction Documentation.  Purchaser and CBC, on the one
          ------------------------------------                                 
hand, and Owner, on the other hand, hereby agree that effective as of the date
on which all of the conditions set forth in Section 1.5 shall have been
satisfied or waived by Purchaser and CBC (the "Effective Date") and without any
further action of any party:

     (a) 1995 Purchase Agreement Amendments.  The 1995 Purchase Agreement is
         -----------------------------------                                 
amended as follows:

          (i) Article 3 thereof is deleted in its entirety and replaced with
     "[intentionally omitted]".

         (ii) Section 9.14, 9.16 and 9.18 thereof each is deleted in their
     entirety and replaced with "[intentionally omitted]".

        (iii) Article 11 thereof is amended by deleting all references to
     Sections 9.16 and 9.18 contained therein.

         (iv) Section 14.5 thereof is deleted in its entirety.

          (v) Section 15.11 thereof is deleted in its entirety.

     (b) Termination of Incentive Compensation Plan.  Owner acknowledges and
         ------------------------------------------                         
agrees that:

          (i) the Westmark Realty Advisers Incentive Compensation Plan (the
     "Incentive Plan") is terminated;

         (ii) Vincent F. Martin, Jr., Bruce L. Ludwig and Stanton F. Zarrow
     resign as members of the Incentive Plan Committee (as defined in the
     Incentive Plan), and appoint Walter V. Stafford, John C. Haeckel and Ronald
     Plakshe to fill the resulting vacancies; and

        (iii) Owner has no interest of any kind, whether presently accrued or
     to accrue hereafter, resulting from, relating to or arising out of,
     directly or indirectly, the Incentive Plan.

     1.3  Release of Purchaser and CBC.  Owner agrees that effective as of the
          -----------------------------
Effective Date and without any further action of any party:

     (a)  Owner, on behalf of himself or herself and on behalf of his or her
heirs, executors, administrators, beneficiaries, assigns, successors, attorneys-
in-fact and anyone claiming an interest through or under any of them
(collectively,

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"Releasor"), unconditionally and irrevocably releases and discharges Purchaser,
CBC and Westmark and all of their respective present and former parent
companies, subsidiaries, predecessors, successors, divisions, partnerships
and/or associated companies, corporations, partnerships and organizations and
all of their present and former officers, directors, employees, agents,
representatives, attorneys, partners, affiliates and stockholders (collectively,
the "Released Parties") with respect to any and all manner of action or actions,
suits, cause or causes of action, in law or in equity or otherwise, claims,
covenants, controversies, promises, contracts, agreements, accounts, payments,
acts, liabilities, obligations, defenses, demands, damages, losses, costs or
expenses of any kind or nature whatsoever, known or unknown, fixed, contingent,
foreseen or unforeseen, suspected or unsuspected, whether presently accrued or
to accrue hereafter, whether or not heretofore asserted (collectively, the
"Claims") which Releasor ever had, now has or may hereafter have against one or
more of the Released Parties resulting from, relating to or arising out of,
directly or indirectly, the payment of Supplemental Purchase Price
(collectively, the "Released Matters").

     (b) This Agreement shall be effective as a full and final accord and
satisfaction of any and all Claims of Releasor as set forth in paragraph (a)
above.  In furtherance of this intention, Releasor acknowledges that he or she
is familiar with any and all rights and benefits which he or she may have under
section 1542 of the Civil Code of the State of California, which provides as
follows:

     "Certain claims not affected by general release.  A general release does
     not extend to claims which the creditor does not know or suspect to exist
     in his favor at the time of executing the release, which if known by him
     must have materially affected his settlement with debtor."

Releasor expressly waives and relinquishes any rights or benefits which he or
she had, now has or may have in the future under section 1542 of the Civil Code
of the State of California, or any similar provision of statutory or non-
statutory law, to the fullest extent that he or she may lawfully waive any such
rights and benefits pertaining to the subject matter of this Agreement.  In this
regard, Releasor acknowledges that he or she is aware that he or she may
hereinafter discover Claims or facts in addition to or different from those
which he or she now knows or believes to exist with respect to the subject
matter of this Agreement, and it is Releasor's intention to fully, finally and
forever settle and release all such Claims.

     (c) Releasor shall not bring, commence, institute, maintain or prosecute or
allow any person, entity or organization to bring, commence, institute, maintain
or prosecute in the name of Releasor, any other action at law or in

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equity, or any legal proceeding whatsoever, in whole or in part upon any fact or
event described or released herein.  This Agreement may be plead as a full and
complete defense to, and may be used as a basis for injunctive relief against,
any action, suit or other proceeding which may be instituted, prosecuted or
attempted in breach of this Section 1.3.

     (d) (i) Releasor acknowledges that he or she has been fully advised with
respect to his or her rights and obligations under this Agreement and
understands those rights and obligations.  Releasor also acknowledges that prior
to the execution of this Agreement, he or she has had an adequate opportunity to
make whatever investigation or inquiries were deemed necessary or desirable with
respect to the subject matter of this Agreement.

          (ii) Releasor acknowledges that he or she has had the opportunity to
seek the advice of counsel regarding this Agreement.  Releasor acknowledges that
whether or not he or she seeks the advice of counsel is his or her prerogative,
and any failure on Releasor's part to seek the advice of counsel cannot be
asserted as a basis to claim that Releasor was unaware of the terms and meaning
of this Agreement.  Releasor acknowledges that the consideration recited herein
is the sole and only consideration for this Agreement and that Releasor has
voluntarily entered into this Agreement.

          (iii)  Releasor understands and agrees that if the facts to which this
Agreement is executed are found hereinafter to be other than, or different from,
the facts now believed by Releasor to be true, Releasor expressly accepts and
agrees that this Agreement shall be and remain effective notwithstanding such
differences in facts.

          (iv)  Releasor warrants and represents that he or she is the sole and
lawful owner of all right, title and interest in and to all the Claims released
herein, and that he or she has not voluntarily, by operation of law or
otherwise, assigned or transferred or purported to assign or transfer to any
other person or entity any Claims, or any part or portion thereof, or any
interest therein.

     (e)  Releasor shall indemnify the Released Parties from and against any and
all liabilities, damages, losses, costs or expenses of any kind or nature
whatsoever, including (without limitation) attorneys' fees and costs of defense,
resulting from relating to or arising out of Releasor's breach of this Section
1.3.

     1.4  Other Agreements. Each of the parties agrees to use best efforts to
          ----------------                                                   
take or cause to be taken, all actions, and to do, or cause to be done, and to
assist and cooperate with the other in doing, all things necessary, proper or
advisable to consummate and make effective the transactions contemplated by

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this Article 1, including the execution and delivery of any additional
instruments necessary to consummate the transactions contemplated by, and to
fully carry out the purposes of, this Article 1.

     1.5  Conditions to Effectiveness.  The effectiveness of the agreements of
          ---------------------------                                         
the parties set forth in this Article 1 are subject to the satisfaction of the
following conditions, unless waived by Purchaser and CBC:

          (a)  Controlling Westmark Owners and Individual Westmark Owners
     entitled to receive at least 95% of the Supplemental Purchase Price (and
     each Controlling Westmark Owner and Individual Westmark Owner that
     currently is an employee of Westmark) shall have executed and delivered to
     Purchaser and CBC an SPP Purchase Agreement in the form hereof;

          (c)  The Note Amendment Agreement, of even date herewith, by and among
     Purchaser, CBC, the Noteholders listed therein and the Westmark Owners
     Representative (the "Note Amendment Agreement") shall have been executed
     and delivered to Purchaser and CBC by the holders of all of the outstanding
     principal amount of the Notes (as defined in the Note Amendment Agreement).


                                   ARTICLE 2

                    REPRESENTATIONS AND WARRANTIES OF OWNERS
                    ----------------------------------------

     Owner represents and warrants to Purchaser and CBC as of the date hereof
and as of the Effective Date as follows:

     2.1  Authority.
          --------- 

     (a) Owner has all necessary right, power, capacity, and authority and has
taken all action necessary to execute and deliver this Agreement, to consummate
the transactions contemplated hereby and to perform his or her obligations
hereunder, and no other proceedings on his or her part are necessary to
authorize this Agreement and the transactions contemplated hereby, and this
Agreement has been duly executed and delivered by Owner and constitutes his or
her valid and binding obligation enforceable in accordance with its terms.

     (b) No consent, approval, order, waiver or authorization is required by or
with respect to Owner in connection with his or her execution or delivery of
this Agreement or his or her consummation of the transactions contemplated
hereby.

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                                ARTICLE 3

              REPRESENTATIONS AND WARRANTIES OF PURCHASER AND CBC
              ---------------------------------------------------

      Purchaser and CBC jointly and severally represent and warrant to Owner as
of the date hereof and as of the Effective Date as follows:

     3.1  Organization.  Purchaser is a limited partnership duly organized and
          ------------                                                        
validly existing under the laws of the State of Delaware. CBC is a corporation
duly incorporated, validly existing and in good standing under the laws of the
State of Delaware.

     3.2  Authority.
     ---  --------- 

     (a) Each of Purchaser and CBC has all requisite corporate or partnership
power and authority to enter into this Agreement and, subject to satisfaction of
the conditions set forth herein, to consummate the transactions contemplated
hereby. The execution and delivery of this Agreement and the consummation of the
transactions contemplated hereby have been duly authorized by all necessary
corporate or partnership action on the part of Purchaser and CBC. This Agreement
has been duly executed and delivered by Purchaser and CBC and constitutes a
valid and binding obligation of Purchaser and CBC enforceable in accordance with
its terms. The execution and delivery of this Agreement does not, and the
consummation of the transactions contemplated hereby will not, conflict with, or
result in any violation of or default (with or without notice or lapse of time,
or both) under, or give rise to a right of termination, cancellation or
acceleration of any obligation or to loss of a material benefit under (i) any
provision of the organizational documents of Purchaser or CBC or (ii) any
material agreement or instrument, permit, judgment, order, statute, law,
ordinance, rule or regulation applicable to Purchaser or CBC or their properties
or assets, other than any such conflicts, violations, defaults, terminations,
cancelations or accelerations which individually or in the aggregate would not
have a Material Adverse Effect (as defined in the 1995 Purchase Agreement) on
Purchaser or CBC, as applicable.

     (b) No consent, approval, order, waived or authorization is required by or
with respect to Purchaser or CBC in connection with the execution and delivery
of this Agreement or the consummation by Purchaser or CBC of the transactions
contemplated hereby.

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                                   ARTICLE 4

                                    GENERAL
                                    -------

     4.1  Notices.  Any notice, request, instruction or other document to be
          -------                                                           
given hereunder by any party to the other shall be in writing and delivered
personally or sent by certified mail, postage prepaid, by telecopy, or by
courier service, as follows:

     if to Purchaser or CBC, to:

          CB Commercial Real Estate Group, Inc.
          533 So. Fremont Avenue
          Los Angeles, CA  90071
          Attention:  Walter V. Stafford
          Fax:  (213) 613-3015

     with a copy to:

          Pillsbury Madison & Sutro LLP
          725 South Figueroa Street, Suite 1200
          Los Angeles, CA  90017
          Attention:  John T. Vangel
          Fax:  (213) 629-1033

     and if to Owner, to:

          as set forth on Schedule 4.1

     with a copy to:

          Stanton H. Zarrow
          865 South Figueroa Street, Suite 3500
          Los Angeles, CA  90017
          Fax:  (213) 683-4201
     and

          Gibson, Dunn & Crutcher LLP
          333 S. Grand Avenue
          Los Angeles, CA  90071
          Attention:  Richard Strong
          Fax:  (213) 229-7520

or to such other persons as may be designated in writing by the parties, by a
notice given as aforesaid.

     4.2  Expenses.
          -------- 

     (a) Except as provided in Section 4.2(b), Purchaser and CBC, on the one
hand, and Owner, on the other hand, shall each pay their own fees and expenses
incurred incident to the preparation and carrying out of the transactions
contemplated herein or in the Note Amendment Agreement.

     (b) On the Effective Date, Purchaser and CBC will pay on behalf of Owner
and the other Controlling Westmark Owners and Individual Westmark Owners who

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shall have executed a SPP Purchase Agreement or the Note Amendment Agreement,
collectively, an amount, not to exceed $30,000, equal to all reasonable,
documented legal fees and expenses of Gibson, Dunn & Crutcher LLP incurred by
such persons incident to the preparation and carrying out of the transactions
contemplated herein or in the Note Amendment Agreement.

     4.3  Amendments.  This Agreement may be amended only by a written
          ----------                                                  
instrument executed by each party hereto.

     4.4  Headings.  The headings of the several sections of this Agreement are
          --------                                                             
inserted for convenience of reference only and are not intended to affect the
meaning or interpretation of this Agreement.

     4.5  Counterparts.  This Agreement may be executed in counterparts, and
          ------------                                                      
when so executed each counterpart shall be deemed to be an original, and said
counterparts together shall constitute one and the same instrument.

     4.6  Binding Nature; Assignment.  This Agreement and all of the provisions
          --------------------------                                           
hereof shall be binding upon and inure to the benefit of the parties hereto and
their respective successors and permitted assigns, but except as otherwise
specifically provided, neither this Agreement nor any of the rights, interests
or obligations of the parties hereto may be assigned by Owner without the
express written consent of Purchaser which consent will not be withheld unless
Purchaser reasonably determines that such assignment will or has a reasonable
likelihood of materially and adversely affecting the benefits to Purchaser of
the transactions contemplated hereby.

     4.7  Applicable Law.  This Agreement shall be governed by, construed and
          --------------                                                     
enforced in accordance with the laws of the State of California as applied to
contracts entered into solely between residents of, and to be performed entirely
in, such state.

     4.8  Dispute Resolution.  Any dispute arising out of or relating to this
          ------------------                                                 
Agreement (or any exhibit or schedule hereto) or the transactions contemplated
hereby or thereby or the breach, termination or validity hereof or thereof,
shall be resolved in the manner contemplated by Section 15.8 of the 1995
Purchase Agreement.

     4.9 Severability.  If for any reason whatsoever, any one or more of the
         ------------                                                       
provisions of this Agreement shall be held or deemed to be inoperative,
unenforceable or invalid as applied to any particular case or in all cases, such
circumstances shall not have the effect of rendering such provision invalid in
any other case or of rendering any of the other provisions of this Agreement
inoperative, unenforceable or invalid.

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     4.10 No Third Party Beneficiary.  Except as expressly set forth herein, no
          --------------------------                                           
provision of this Agreement, including the Exhibits and Schedules hereto, is
intended or should be construed to create any third party beneficiaries or to
give any rights, including rights of subrogation, to any person other than the
parties to this Agreement.

     IN WITNESS WHEREOF, Purchaser, CBC and Owner have caused this Agreement to
be signed all as of the date first above written.



                         WESTMARK REAL ESTATE ACQUISITION PARTNERSHIP, L.P.
                         By:  CB COMMERCIAL REAL ESTATE GROUP, INC., its general
                              partner


                              By _______________________________________________



                         CB COMMERCIAL REAL ESTATE GROUP, INC.



                         By ____________________________________________________



                         OWNER:


                         _______________________________________________________
 

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