1. Call him again...If he answers you can say"I am on speaker phone, trying to multitask" or something like that. That makes the conversation "public" and legal to record if you want to.
2. Send "demand" letter. This is basically what you expect him to do about the money he owes you. He is probably well aware that he can only be sued in HIS State. Try and make it polite. If you know someone in Florida, and can "document" what happened or get him to admit on recording, then you have something on him and could possibly "sell" the liability to someone there(i don't know if this works, but it is an idea) and they could sue him.
3.Find cell numbers:his,wife,kid,cousin...ect. start calling at all hours.
I once got back over 2 grand from someone in England who sold me something he didn't own. That took a few months and went past suggestion number 3. YMMV.
Best bet to to remain calm(u've done a fair job here, I would have already been on a plane long ago). YMMV