In most States in this country when you purchase property at a trustee's sale (foreclosure sale) the winning bidder is required to either pay the entire purchase price on the spot through a cashier's check or the entire amount within a stated time period under the laws of the State that the property is in.It would appear at first blush that under the law of the State where the property is located and where you are the winning bidder at a trustee's sale, you are required to pay the trustee for the sale of the property the entire amount of the purchase within the time period mandated by State law.You are legally bound to go through with the transaction. if you do not, the trustee under the mortgage very well could file a lawsuit against you for not complying with the bid process that you won.