The council shall provide by ordinance for the purchasing procedure to be followed in all purchases, sales and leases and the letting of contracts therefor subject to the following restrictions:
(a) All purchases and sales and leases shall be evidenced by written contract or purchase order.
(b) No contract shall be made with any person who is in default to the city.
(c) Sealed bids shall be obtained for the purchase, sale or lease of personal property in amounts over two thousand dollars and for the purchase, sale or lease of real property in amounts over five thousand dollars, except where the council shall determine by unanimous resolution of those present at a regular meeting that the public interest will be best served without the taking of bids.
(d) The council may authorize the making of public improvements or the performance of any city work by any city agency without competitive bidding. The council may reject any or all bids or parts of bids. When one or more parts of a bid are rejected, the council may accept any part or parts which are not rejected.
(e) No public work, or improvement[,] shall be commenced, nor any contract therefor be let or made, until a valid specific appropriation to pay the cost thereof shall have been made by the council from funds on hand and legally available for such purpose, or until a tax or assessment shall have been levied or bonds authorized and sold to pay the cost and expense thereof.
(f) Any agreement or contract for the renting or leasing of public property to any person for a period longer than three years shall be subject to the same referendum procedure as is provided in the case of ordinances passed by the council[,] but any petition for such referendum must be filed within thirty days after publication of the proceedings of the meeting of the council at which such agreement or contract is authorized.
(g) The transfer or assignment of any agreement or contract for such renting or leasing of public property may be made only upon approval of the council[,] but the approval of such transfer shall not be subject to referendum.
(h) Rentals and leases, and renewals thereof, shall be for a fair consideration as determined by the council.