Are you still friends with the guy?
If you are, you could invite him out somewhere (take him on a camping or hunting trip with you), get him drunk, then beat the shit out him. Problem is, he'll be seeking revenge on you if you don't kill him.
Even if you do something else to him and he suspects it was you, he's going to want revenge. It'll just end up being one big vicious circle of violence.
I can't find his home address. I've tried. I know he is looking for a place to live. I sent him a harmless message tonight. I doubt he will write back.
Jerry the other guy is a total idiot whose probably braindead that's how stupid he is. It'd be like asking a dog to help you. Only a dog has a higher IQ.
You could just drop it to him lightly that you would really appreciate your money back because you would hate to have to resort to other means such as destroying something of his, be sure no one else is around to witness the conversation. He will want to know exactly what you mean and you can just tell him to use his imagination.
If he doesn't give you your money back slit his tires and use an icepick, it effective and quiet. For me that is total satisfaction, I wouldn't even want the money anymore and I got my point across.
Why do anything criminal thats going to cost you well over 300 bucks.
Ask jerry to pay back the money or ask help to set up a fundraiser if he cant afford it.
Create a facebook campaign and publicize it to all his coworkers and friends to chip in 3 to 30 bucks to help Jerry do the right thing
You will probably make more than 300 instead of incurring 1000s in legal costs by doing anything illegal. Doing a charity fundraiser is perfectly legal as long as you dont commit slander libel harassment fraud etc. Keep it charitable and your friend(s) will get the msg