(1) Except in the purchase of unique articles or articles which, for any other reason, cannot be obtained in the open market and except as otherwise provided in this section and in section 24, competitive bids shall be secured before any purchase or sale, by contract or otherwise is made or before any contract is awarded for construction, alterations, supplies, equipment, repairs, or maintenance or for rendering any services to the authority other than professional services; and the purchase shall be made from or the contract shall be awarded to the lowest responsive and responsible bidder; or a sale to the highest responsive and responsible bidder. The authority may reject any and all such bids or proposals. A purchase of any unique article or other articles which cannot be obtained in the open market shall not be made without express approval of the board where the amount involved is in excess of $25,000.00.

    (2) All purchases and sales in excess of $25,000.00 shall be awarded after advertising in a local newspaper of general circulation in the metropolitan area at least 2 weeks before the bid opening. Bids shall be publicly opened and read aloud at a date, time, and place designated in the invitation to bid. Invitations to bid shall be sent at least 1 week before the bid opening to at least 3 potential bidders who are qualified technically and financially to submit bids, or a memorandum shall be kept on file showing that less than 3 potential bidders who are so qualified exist in the market area within which it is practicable to obtain bids.

    (3) Except as otherwise provided in this section, written price quotations from at least 3 qualified and responsible vendors shall be obtained for all purchases and sales of $25,000.00 or less but over $5,000.00, or a memorandum shall be kept on file showing that less than 3 vendors so qualified exist in the market area within which it is practicable to obtain quotations.

    (4) Purchases or sales under $5,000.00 may be negotiated with or without competitive bidding under procurement procedures as promulgated and established by the general manager.

    (5) Competitive bidding requirements may be waived if it is determined by the general manager, or in such other manner as the board may provide, by regulation, that an emergency directly and immediately affecting service, or public health, safety, or welfare requires immediate delivery of supplies, materials, equipment, or services.

    (6) Savings achieved by the 1993 amendatory act that added this subsection shall be used as 1 funding source for funds to construct bus shelters at SMART bus stops. In the case of a state trunkline highway, a bus shelter constructed by SMART may include advertising on the shelter. This project shall be competitively bid and shall be completed within 12 months.