Any person, including the association, shall be authorized to bid for the unit at the public sale and to purchase the unit. The highest bidder who meets the requirements of the terms and conditions of the public sale shall be the successful bidder. The public sale shall be considered as being held when the unit is declared by the association as being sold to the successful bidder. When the public sale is held, the successful bidder at the public sale, as the purchaser, shall make a nonrefundable downpayment to the association of not less than ten per cent of the highest successful bid price. If the successful bidder is the association, the downpayment requirement may be satisfied by offset and a credit bid up to the amount of the lien debt.