The procedures specified in Sections 1500 through 1505 of this title shall not apply to the receipt of or the purchases, lease-purchases and rentals of supplies, materials, equipment and improvements made with funds of a public trust expended by a county on behalf of such public trust, if the county is a beneficiary of such public trust and such public trust receives and administers the proceeds of sales tax.
Okla. Stat. tit. 19, § 1505.2