回复：房产交易合同的效力

if the seller repudiates the contract, he needs to return the deposit. If the buyer suffers loss because of the repudiation (for example, he had to buy some property much higher than the market price due to the repudiation, the breaching party needs to pay the damages as well).  Or, the buyer's damages can be calculated by the inequitable profit procured by the seller due to the repudiation.