The commission shall determine the rate of interest bonds issued under this chapter shall bear, the time or times of payment of such interest, the form of the bonds, and the manner of executing the bonds, and shall fix the denomination or denominations of the bonds and the place or places of payment of principal and interest thereon, which may be at any bank or trust company within or without this state. The bonds shall be sold at public sale or private sale and at such price or prices as the commission shall determine.