(a) A person exercising the privilege of producing for sale, profit or commercial use, any natural resources, product or manufactured product, and either engaged in the business of selling such product not otherwise exempted herein, or engaged in a business or activity in which such natural resource, product or manufactured product is used or consumed by him and such use or consumption is not otherwise exempt under this article, shall make returns of the gross proceeds of such sales or, in the absence of sale, the gross value of the natural resource, product or manufactured product, so used or consumed by him and pay the tax imposed by this article.
(b) The Tax Commissioner shall promulgate such uniform and equitable rules as he deems necessary for determining the gross value upon which the tax imposed by this article is levied in the absence of a sale, which value shall correspond as nearly as possible to the gross proceeds from the sale of similar products of like quality or character by the same person or by another person.
(c) The provisions of this section, as amended by this act, shall apply to natural resources, products or manufactured products, used or consumed by the producer or manufacturer thereof on or after May 1, 1989.