That's unfortunate, it seems odd to me that they would expect clients to travel as far as many do with that much cash on their person. Did they refuse to fly you out unless you paid the extra $1,500? What would they do if you lost your wallet or didn't happen to bring enough? It's not as if this is some hole in the wall restaurant, credit cards are the norm nowadays, even out in the boonies.
While it is perfectly legal to do business in cash, given their reputation here a mention of the IRS might be enough to sway them to refund your non-existent flight. I absolutely despise fighting with people over my money, and I tend to get rather nasty about it if they ignore me repeatedly.
