The governing body of the county may provide for the registration of such bonds in the name of the owner as to the principal alone or as to both principal and interest. Such bonds must be sold in such a manner as the governing body of the county may determine to be for the best interests of the county, taking into consideration the financial responsibility of the purchaser and the terms and conditions of the purchase, and the availability of the proceeds of the bonds when required for payment of the costs. The proceeds of such bonds shall be deposited with such depositories as the governing body of the county shall approve, shall be secured in such manner and to such extent as the governing body of the county shall require, and shall be used solely for the payment of the costs of the bridge and costs incident thereto.