The authority may sell such bonds in such manner and for such price as it may determine to be for the best interests of the authority. The proceeds of the bonds shall be used solely for the payment of the costs of the project or projects and shall be disbursed upon requisition or order of the chairman of the authority under such restrictions, if any, as the resolution authorizing the issuance of the bonds or the trust indenture hereinafter mentioned in this chapter may provide. If the proceeds of the bonds, by error of calculation or otherwise, shall be less than the cost of the project or projects, unless otherwise provided in the resolution authorizing the issuance of the bonds or in the trust indenture, additional bonds may in like manner be issued to provide the amount of the deficit, which, unless otherwise provided in the resolution authorizing the issuance of the bonds or the trust indenture, shall be deemed to be of the same issue and shall be entitled to payment from the same fund without preference or priority of the bonds first issued for the same purpose. If the proceeds of the bonds of any issue shall exceed the amount required for the purpose for which the bonds are issued, the surplus shall be paid into the fund hereinafter provided for the payment of principal and interest of such bonds.