The bonds must be offered for competitive bids from recognized financial investment institutions before the bonds may be sold: Provided, That the bid process is not subject to the provisions of article three-a, chapter five-a of this code. Any and all of the bids may be rejected. If the bonds are not sold pursuant to the competitive bid process, the bonds may, within sixty days after the date the bids are received, be sold at private sale: Provided, however, That no private sale shall be made at a price less than the highest bid received.