It shall be the duty of the commissioners to purchase all supplies for the maintenance of the inmates of the institutions under their supervision, and to contract for and purchase all services and personal property for county institution district officers and agencies. They shall where possible anticipate the needs of the various officers and agencies of the district, and endeavor to purchase in wholesale quantities where practicable and where savings could be achieved thereby. The commissioners may make contracts and purchases for all purposes expressly or impliedly authorized by law.

All contracts and purchases made by the commissioners for the county institution district shall be made in the same manner and under the same procedure as if they were being made for the county, and shall be subject to the same restrictions, regulations and controls provided by law for county contracts and purchases.

The provisions of the second paragraph notwithstanding, the commissioners may enter into contracts and make purchases for hospitals which are part of the institution district, by purchasing off or participating in contracts for materials, supplies and equipment entered into by a nonprofit cooperative hospital service association.