Except as otherwise provided by law or rules adopted by the governor, the sale by any governmental office, department, board, establishment, institution, or agency (hereafter referred to as “agency”) of domestic animals such as hogs, poultry, etc.; of the produce of animal husbandry; of fruits, vegetables, and other agricultural produce; of manufactured articles; or the like (hereafter referred to as “products”) where the raising, production, or manufacture of the same is a part of the usual or authorized activities of the agency, may be made by the agency in a manner to be determined by the head of the agency. The proceeds of the sales, where not otherwise provided by law, shall be paid into the general fund as state realizations. If any of the products are sold from one agency to any other agency, a reasonable sale price may be paid to the selling agency by the purchasing agency and credited to the current expense appropriation of the selling agency, subject to re-expenditure during the fiscal or other period in which the current expense appropriation is available, and any unexpended balance shall lapse at the end of the period. This section shall not apply to public school activities, such as the sale of food in public school cafeterias, the proceeds of which are not considered as public funds payable into the treasury of the State, nor shall the same apply to activities of the University of Hawaii. Nothing in this section shall be deemed to prohibit a transfer from one agency to another of the products without charge, if so ordered by the selling agency.