Given that they advertised it, I would definitely talk to your state attorney or however the system works in the US, on the grounds of fals advertising. I heard of a story somewhere about a guy who saw a dealer ad saying he could buy a car for 1,000 bananas (an odd reference to money, imo). When the dealer refused to accept the bananas he showed up with, he took action for false advertising and ended up getting his car for 1,000 bananas.
Its worth a shot anyway. Any business who treats customers like that doesn't deserve to be in business.
I don't know if your local news has a "troubleshooter" (someone who investigates things like this) but you could give them a call also. The dealership is a business and negative press is a good way to effect their business with no out of pocket expense. Usually just the call from a tv station saying they are going to run a story like this makes things happen in the consumers favor.