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                                                                    EXHIBIT 10.7

                THIRD AMENDMENT TO REAL ESTATE PURCHASE AGREEMENT

      This Third Amendment to Real Estate Purchase Agreement ("Amendment") is
made and entered into as of the 2nd day of November, 2004, by and between
WARBURG-STORAGEMART PARTNERS, L.P. ("Buyer" or "Purchaser") and CHICAGO I
SELF-STORAGE, LTD., an Illinois limited partnership ("Seller").

      This Amendment is made in view of the following facts:

A. Seller and Buyer entered into a Real Estate Purchase Agreement dated as of
September 14, 2004 (the "Contract"). Capitalized terms used herein but not
defined herein shall have the meanings given them in the Contract.

B. Seller and Buyer entered into an amendment to the Contract pursuant to a
letter dated October 29, 2004, executed by counsel for Seller and Buyer (the
"First Amendment") and pursuant to a letter dated November 1, 2004, executed by
counsel for Seller and Buyer (the "Second Amendment").

C. Seller and Buyer desire to amend the Contract in certain respects.

      NOW THEREFORE, Seller and Buyer agree as follows:

      1. REDUCTION OF PURCHASE PRICE FOR ASBESTOS REMEDIATION: As part of
Buyer's due diligence inspections regarding the Property, Buyer obtained a study
concerning whether the Property contains asbestos and asbestos-containing
materials (collectively "ACM"). Such study concluded that the Property does
contain ACM and that the ACM should be removed, contained and otherwise
remediated. Buyer's consultants concluded that the cost to remove, contain and
remediate the ACM will be $43,347.00. The Buyer and Seller agree that the
Contract is amended to reduce the Purchase Price by the amount of $43,347.00. In
consideration of the reduction of the Purchase Price as agreed in this paragraph
1 of this Amendment, Buyer agrees that Seller shall have no obligation to take
any actions to remove, contain or otherwise remediate any of the ACM, and Buyer
shall purchase the Property subject to the ACM and shall assume all liability
and responsibility with respect to the ACM.

      2. TENANT ESTOPPEL CERTIFICATES: Buyer has prepared and delivered to
Seller and has requested Seller to assist in obtaining execution of tenant
estoppel certificates ("Estoppel Certificates") for tenants who have leased
space in the Real Estate (those tenants being Sprint Com, Inc., Advance Event
Group, Inc., ATT & T Wireless PCS, Inc., and Cook Inlet / Voice Stream PSC,
L.L.C.). Buyer recognizes that Seller has no obligation under the Contract to
obtain execution of the Estoppel Certificates. However, Seller agrees to use its
best reasonable efforts to assist Buyer in obtaining the signatures of the
Tenants on the Estoppel Certificates, and specifically Seller agrees that Seller
will present the Estoppel Certificates to the tenants, will

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request that the tenants execute the Estoppel Certificates, and will take such
other action as may be reasonably necessary to obtain execution of each of the
Estoppel Certificates. However, Buyer recognizes that neither the execution nor
the delivery of the Estoppel Certificates, or any of them, shall be conditions
precedent to the Buyer's obligation to close.

      3. CRITICAL WALL REPORT: Seller shall cause an update or supplement to the
"critical wall" report of the Property to be submitted to the City of Chicago,
Illinois (the "City") prior to Closing. In consideration of the Seller's
obligations undertaken in this paragraph 3 of this Amendment, Buyer and Seller
agree that the Purchase Price is increased by the amount of $7,500.00. The
updated critical wall report shall contain an amount that the Seller's
consultant reasonably expects will be required to be expended to comply with the
City's requirements regarding the critical wall report (such amount being
referred to as the "Repair Amount"). If the updated or supplemental critical
wall report reveals or indicates that the Repair Amount is up to but not in
excess of $50,000.00, then the Seller shall cause all such repairs or other work
to be done prior to the Closing; provided, however, that if the repairs or other
work cannot reasonably be completed prior to Closing, then the Closing shall
take place without the additional work and repairs being completed, the Purchase
Price shall be reduced by the Repair Amount, Buyer shall assume all obligations
with respect to performing all critical wall work and repairs, and Seller shall
be released from any further obligations in that regard. However, if the updated
or supplemental report indicates that it will cost in excess of $50,000.00 to
maintain the Property's compliance with the requirements relating to the
critical wall report, Seller shall give written notice thereof to Buyer (the
"Critical Wall Notice"). The Critical Wall Notice shall include a detailed
analysis of what will be required in order to maintain compliance with the
critical wall requirements and a detailed cost breakdown. Within five (5)
business days after receipt of the Critical Wall Notice, the Buyer shall elect,
in writing, whether the Buyer will (1) proceed to closing with a reduction in
the Purchase Price of $50,000.00, or (2) terminate the Contract. If the Buyer
elects to proceed to Closing, then the Purchase Price shall be reduced by
$50,000.00, Buyer shall assume all obligations with respect to performing all
critical wall work and repairs, and Seller shall be released from any further
obligations in that regard. If the Buyer elects to terminate the Contract, the
Contract shall be terminated and Buyer shall receive a full refund of the
earnest money deposit. In the event that Buyer gives no written response within
five (5) business days after receipt of a Critical Wall Notice, then Buyer shall
be deemed to have elected to proceed to closing and to have the Purchase Price
reduced by $50,000.00.

      4. PURCHASE PRICE: After taking into consideration the modifications to
the Purchase Price as stated in paragraphs 1 and 3 of this Amendment, the total
Purchase Price shall be $6,914,153.00. All references in the Contract to the
Purchase Price are amended to mean and refer to the amount of $6,914,153.00.

      5. RATIFICATION: Subject to the foregoing modifications, and subject to
the modifications contained in the First Amendment and the Second Amendment,
Buyer and Seller

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ratify and reaffirm the Contract. No amendments to the Contract are intended by
Buyer and Seller except as specifically stated herein.

      IN WITNESS WHEREOF, the Buyer and Seller have executed this Amendment as
of the 2nd day of November, 2004.

                                     WARBURG-STORAGEMART PARTNERS, L.P.
                                     ("Buyer")

                                     By:  SMP Management, L.L.C.,
                                          General Partner

                                          By:    _______________________
                                          Name:  _______________________
                                          Title: _______________________

                                     CHICAGO I SELF-STORAGE, LTD.. ("Seller")

                                     By:  Chrisken Partners Cash Income
                                          Fund, L.P., General Partner

                                          By:    Chrisken Income Properties,
                                                 Inc., Managing General
                                                 Partner

                                                 By:    __________________
                                                 Name:  __________________
                                                 Title: __________________