Section 4-2 Purchases And Sales.
   1. The city manager, subject to any regulations which the council may prescribe, shall contract for the purchase, or issue purchase authorizations for, all supplies, materials and equipment for the offices, departments and agencies of the city government. Every such contract or purchase exceeding an amount to be established by ordinance, shall require the prior approval of the council. The city manager also may transfer to or between offices, departments and agencies, or sell, surplus or obsolete supplies, materials and equipment, subject to such regulations as the council may prescribe;
   2. Before the purchase of, or contract for, any supplies, materials or equipment, or the sale of any surplus or obsolete supplies, materials or equipment, ample opportunity for competitive bidding, under such regulations, and with such exceptions, as the council may prescribe, shall be given; but the council shall not except a particular contract, purchase or sale from the requirement of competitive bidding; and
   3. The council by ordinance may transfer some or all of the power granted to the city manager by this section, relating to purchases and sales, to an officer appointed by and subordinate to the city manager.