If you have your heart set on a Thompson Center rifle, especially a flintlock, that is a very fair price for a new in the box rifle. A Thompson Center rifle is a great rifle. They are a very good quality rifle.
If what you want is a good flintlock, there are other brands out there as well. BUT I can sure understand why you'd want a Thompson Center.
Also I agree that there are some real good used Thompson Center rifles out there if you watch the auction sights.