If a buyer offers a certified check or money order for more than the asking price was or the agreed price and then asks for the difference to be given back in some way this is a scam. This is how "boats for sale" are used to steal funds with counterfeit certified checks or money orders Use extra caution with foreign transactions. Make sure you do some research on your buyer. If you feel that you are working with someone that is trying to pull a scam please contact the proper authorities.