(a) Every municipality may provide for the centralized purchasing of materials, supplies and equipment; and the term "equipment," for the purposes of this section, shall include, but not be limited to, motor vehicles. Every municipality may, by agreement with the state director of the division of purchases of the department of finance and administration, purchase the same through such department, or may enter into agreements with one or more other municipalities, counties or county boards of education, or any combination thereof, for centralized purchasing for all governmental units which are parties to such agreement.
(b) Every municipality is hereby empowered and authorized to provide by ordinance whether competitive bidding is to be required in the purchase of materials, supplies and equipment and if so the type or types of purchases with respect to which the same shall be required and the method and manner in which bids shall be obtained. Any ordinance adopted by any municipality in accordance with the provisions of this subsection (b) shall supersede any provision pertaining to competitive bidding contained in the special legislative charter of such municipality.