All agencies shall submit to the Commissioner of Property and Procurement, at such times and in such form as he shall prescribe, reports showing stocks of all supplies, materials, and equipment which are no longer used or which have become obsolete, worn out or scrapped. The Commissioner may transfer such stock to another or other agencies which have need for and can use it. The Commissioner may sell all such supplies, materials and equipment which have become unsuitable for public use, or exchange for or trade in the same on new supplies, materials, and equipment. Any such sale, exchange or trade-in shall be based on competitive bids secured in accordance with the provisions of this chapter; provided, that any such sale, exchange or trade-in may be made by public auction in such cases as the Commissioner shall determine that the cost of formal advertising would exceed the proceeds from the sale, exchange or trade-in of the surplus stock.