No municipality shall have the power to pay out of its general funds or otherwise contribute any part of the costs of acquiring a project, and shall not have the power to use land already owned by the municipality, or in which the municipality has an equity, for construction thereon of a project or any part thereof; provided, however, that municipal property which is not needed for public or municipal purposes may be sold for fair market value or leased for fair market rental for a project; such fair market values to be conclusively determined by the governing body of the municipality owning such property. The entire cost of acquiring any project must be paid out of the proceeds from the sale of bonds issued under the authority of this article; provided, however, that this provision shall not be construed to prevent a municipality from accepting donations of property to be used as a part of any project or money to be used for defraying any part of the cost of any project.