When selling stuff, I always give buyers leeway. Good stores do that for long term business. I also offered a fistful euros to break up the deal and then upped the euros. I've been pretty generous. Clearly he knows it's a hoax as why in Earth would he not take compensation for his trouble especially if he truly believed it was genuine and he could sell it for that amount again. In my state, the law is actually on my side at least when it comes to vehicle and house sales. (I suspect it does for cheaper items as well but I just don't know. For cars and houses definitely know as the dealers are required to inform you of that law!)
So "buyer beware" and the actually isn't true anymore at least legally.