I hope you haven't been scammed, TWR, but alas your buyer would not have got such a deal from me. When dealing with people I do not know I have long since adopted a stance which one of my uncles, who was a Detective Chief Inspector in the Met, passed on to me:
"Trust nobody, believe nothing, check everything"
It's sometimes a pain but I make it a firm rule and it's served me quite well over the years. Regretably there are far too many people around who make it their business to turn others over at any and every opportunity and there are too few people like me - distrusting bar stewards - who refuse to let them do so.