Read the TOS for the auction.
Quote:
We reserve the right to end the listing if the vehicle is no longer available for sale.
The deal they made with the other person isnt your problem, neither is the internet guy being out of town. You agreed to the terms of sale when you bid on the car. They are the ones that dropped the ball by not removing the auction when the car was sold. Since the listing was not ended early, the car was sold to you, per the terms of sale that they wrote.
Got to love the the small stuff. Wonder if it would hold up in court if you really wanted to push the issue.