It's always going to be hard to tell with used. Maybe you paid more than someone else could have? Maybe I could have gotten my car for less too? Who knows. Dealer needs to make a little money off sales though. Depends on what your trade value was.. what fees there were.. condition of car.. what it's past life was like.. what time of the month it is..
With new you can base price off invoice/msrp and work from there. Then we could tell you if you overpaid