Truth of the matter is, a 4 door is worth less then a 2 door as they are less desirable, unless the potential buyer wants a 4 door, which in this case as your car is auto makes it worth less again.
I personally found when buy/selling gtst’s, gts4’s were less wanted. Your car also has the “tweedy” fabric, which is less desirable.
It’s not worth $10k, as you can pick up R33’s for that. It’s worth about $7k - $8k (in my opinion).