The vendor was a little slimy for keeping any of your deposit, if you ask me.
Well if he was holding the gun not to sell it to anyone else and you gave him a deposit expressly for that purpose there is a good argument he ought not return any of it. If no one else came along asking and I were the the guy I would have simply returned it all.
I must agree with the sentiments above about gun show prices. I've never seen any gun stuff there that I could not get less somewhere else. My best scores at a gun show were a free hat that the marines gave me for doing 20 pull-ups at their booth and a used video game lol.
My local classifieds are about as bad. People asking more for their used bushmasters than I paid for my Noveske. Most of it is pretty laughable. Any good deals get snatched up quick so if you are in the market for something you need to be vigilant about watching know the price at which you will buy and jump on it.