The governing body of the governmental unit shall issue the bonds of the governmental unit not exceeding the amount named in the resolution. Such bonds shall become due not more than 30 years after their date, shall be in denominations of $100 or any multiple thereof, and shall bear interest, at a rate not exceeding the maximum rate authorized by the Bond Authorization Act, as amended at the time of the making of the contract, for bonds issued before January 1, 1972 and at a rate not exceeding the maximum rate authorized by the Bond Authorization Act, as amended at the time of the making of the contract, for bonds issued after January 1, 1972, payable semiannually, as shall be determined by the governing body. Such bonds shall be sold in competitive bids; and the governing body may, if it is of the opinion that the bids are unsatisfactory, reject the bids and re-advertise and solicit other bids.
     With respect to instruments for the payment of money issued under this Section either before, on, or after the effective date of this amendatory Act of 1989, it is and always has been the intention of the General Assembly (i) that the Omnibus Bond Acts are and always have been supplementary grants of power to issue instruments in accordance with the Omnibus Bond Acts, regardless of any provision of this Act that may appear to be or to have been more restrictive than those Acts, (ii) that the provisions of this Section are not a limitation on the supplementary authority granted by the Omnibus Bond Acts, and (iii) that instruments issued under this Section within the supplementary authority granted by the Omnibus Bond Acts are not invalid because of any provision of this Act that may appear to be or to have been more restrictive than those Acts.