Sorry I have to add my two cents. I don't think this was a scam, just happens that you have shitty luck. I bet anyone here would have done the same thing if somebody offered a significantly higher dollar for the moped. Some may not admit it but I'm sure they agree. Kinda sad to say but money talks.
I'd be pissed too and probably vent a little as you did but put the shoe on the other foot for just a second and think about it.
You'll find another ped, took me a while as well.