They can sell to whomever they wish. A deposit is not a legally binding contract. Probably got offered more money from them.
The only recourse is to get your deposit back, nothing more, nothing less. If they refuse, you can sue them in small claims court.
Maybe if you complain to the general manager or the owner of the dealership, they may do the right thing and give you a fantastic deal on another car. If they ignore you, you could try filing a complaint with BBB.org and State Attorney. Not much will be done but maybe other shoppers will be forewarned about doing business with those sleazeballs.