Well, you and your buddy have another issue... and that's between you and him to work out. I don't know all of y'alls details, but it sounds like you got the shaft a couple times in that deal.
As for the importation of stingrays using a vendor's import license... I dunno. I've been screwed by a middleman before, too. Lost nearly a grand to that douchebag that ran MassiveAggression. But, you live and you learn. This was years ago, so don't make fun of me too hard for dealing with that loser.
I guess the middleman takes a cut of the money, so maybe he should "at least" pay you back that money. Not sure about the total amount. Depends on what the terms were that you agreed on. Every case is different. Like I said before, I feel for you. This hobby has a lot of scammers, but there are some honest people around, as well. Trust your gut.