Revenue bonds may be issued, as provided in section 28F.3, to provide all or any part of the funds required to finance the cost of the acquisition, construction, reconstruction, repair, extension or improvement of any project or projects or other purposes authorized under this chapter and such cost shall include, but shall not be limited to, administrative expenses, acquisition and construction costs, engineering, fiscal or financial and legal expenses, surveys, plans and specifications, interest during such construction, reconstruction, repair, extension or improvement or acquisition and for one year after completion of such construction, reconstruction, repair, extension or improvement or after acquisition of the project or projects, initial reserve funds, acquisition of real or personal property, including franchises, and such other costs as are necessary and incidental to the construction, reconstruction, repair, extension or improvement, or acquisition of such project or projects and the financing thereof. Such an entity shall have the power to retain and enter into agreements with engineers, fiscal agents, financial advisers, attorneys, architects or other consultants or advisers for planning, supervision and financing of such project or projects upon such terms and conditions as shall be deemed advisable and in the best interest of the entity. Bonds issued under the provisions of this chapter are declared to be investment securities under the laws of the state of Iowa.