Yea. I found the auction you were talking about. There's no way to tell from the pic if it's a custom job. If he can't provide any proof that a variant exists, and especially can't tell you the history of that figure, I would stay away from it.
So how many of the old Knickerbockers do you have in your collection? I'm a big fan of the new line that's out, but I don't own any of these. I know they are quite expensive.