Don't stop on this for the sake of it being 400 dollars. IT'S YOUR MONEY!!! He is trying to steal, and its wrong. This is why people are scared to make deals on forums. You can get great deals from honest people then people like him come in and mess it all up.
I know this sounds like something that someone would just say, but if you go to his door just go, take a friend and break his legs. Photograph it and post it from a library to reduce the risk of being caught. Perhaps he won't just laugh about stealing money from his wheelchair. Wow, I just realized that this guy is seriously pissing me off. LOL