If you can do it for $4,000. I'd say you are doing something. There's several thousand dollars difference between the cars, how they are equipped could mean several thousands. And the 05 is used. Depreciation alone could easily be $4,000 before you compare the V6 to the V8.
I wish you luck.
If you can do it for $4,000, many of us would probably won't to know the name of the dealer making such good offers when GTs are so hard to find.