After being a victim of a “scam” myself when buying a domain that claimed X amount of revenue, I can tell you that only a civil suit is viable. The reason being, from a legal standpoint in the US, anything under $50,000 and without numerous complaints is not punishable by law. Sorry to bear the news, but if you have the time, atleast try to scare that person into giving you some money back, else there is little to do aside from small claims court.