State Farm is a terribly insurance company, they commonly try to worm their way out of paying legitimate claims.
You did 2 things wrong here; first, ALWAYS call the cops when an accident occurs. Before this Asshole had the chance to talk himself out of feeling bad for a shitty driving move that could have gotten you killed, he would have admitted to the cop at the scene what happened. This would have resulted in a ticket for failure to yield, giving State Farm less of an argument to worm out of paying (although there is no guarantee, we are talking about State Fucking Farm here).
Second, you should have gotten an estimate from the dealer for full repair and ask for nothing less than that. Submitting some arbitrary number based on your own work and used parts will never impress an insurance adjuster, it only makes him think you are easily blown off.