EXHIBIT 5.1

                         Opinion and Consent of Counsel

THE O'NEAL LAW FIRM, P.C.
668 North 44th Street, Suite 233
Phoenix, Arizona 85008
(602) 267-3855 (602) 267-7400 (fax)

                    OPINION OF COUNSEL AND CONSENT OF COUNSEL

TO:      Board of Directors
         Winmark, Inc.

RE:      Registration Statement on Form SB-2

Dear Mr. Winstein:

As  counsel to  Winmark,  Inc.,  (formerly  Ecostructure  Corporation)  a Nevada
corporation  (the  "Company"),  we have  participated  in the preparation of the
Company's  Registration  Statement  on Form SB-2 filed with the  Securities  and
Exchange Commission pursuant to the Securities Act of 1933, as amended, relating
to the  registration of 500,000 shares of the Company's  $0.001 par value common
stock.  As counsel to the Company,  we have  examined  such  corporate  records,
certificates  and other  documents  of the Company,  and made  inquiries of such
officers of the Company, as we have deemed necessary or appropriate for purposes
of this opinion.  We have also examined the applicable  laws and  constitutional
provisions of the State of Nevada, and reported judicial decisions  interpreting
such laws and provisions.  Based upon such  examinations,  we are of the opinion
that the shares of the  Company's  common  stock,  when issued in the manner set
forth in the  Registration  Statement,  will be validly  issued,  fully paid and
non-assessable  shares of the  shares of the  common  stock of the  Company.  We
hereby  consent  to  the  inclusion  of  this  Opinion  as  an  exhibit  to  the
Registration  Statement  on Form SB-2 filed by the Company and the  reference to
our firm contained therein under "Legal Matters".

                                                     Sincerely,



                                                 /s/ THE O'NEAL LAW FIRM, P.C.
                                                     Phoenix, Arizona

                                                 DATED: August 10, 2004


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