My neighbor sold a firearm for $60.00 to local gun store. He used that $60.00 towards the purchase of another firearm. The gun store deducted $60.00 off the price of the new firearm. He then decided that he didn't want the new firearm. The gun store refunded the purchase price which was reduced by the $60.00 sale of his firearm. He feels he was cheated because he got the reduced purchase price refunded and they kept his firearm saying they already bought it and could not just give it back to him. He feels he's owed the $60.00 for his original firearm. Who's right here?