This is a civil case; not a criminal case.  There won't be any response from the police.  The prospective buyer might file a lawsuit in Small Claims Court to try to recover the deposit, but should not prevail because the buyer was informed that the deposit was non-refundable.  It would have been preferable if that non-refundable statement had been in writing.  You can also claim that your basis for retaining the non-refundable deposit is that you lost potential sales to others by holding the RV for this particular buyer, who subsequently backed out of the transaction.