If all bids are rejected, the board, by private negotiation, may sell and convey the property or any part thereof for cash at not less than the appraised value thereof, or may agree to sell and convey the property at not less than the appraised value for part cash and part in deferred payments bearing interest at such rate as shall be agreed to mutually between the board and the purchaser. The title to any property so sold shall remain in the district until the purchase price thereof has been fully paid. All moneys realized from the sale of the property shall be deposited with the county treasurer designated as the custodian of district funds, and such moneys shall be paid out only upon warrants duly authorized by the board and signed by the chairman and secretary thereof.