Off the top of my head, that sounds a bit high, but not totally outrageous. There are a lot of factors involved in the pricing--such as where you live--and also there is, of course, always a range that is average for a car of a certain specification. Dealers always sell a bit higher. I would suggest looking at Autotrader and Carmax and trying to find a GTO in your state that is as close to year/mileage as this one and compare the prices. Even if you can't find one with 4k miles, but instead find a few with 2k and 7k, it should give you a better feel for pricing.