Roush's and Saleen's are nice, but they're a tad overpriced IMO. I remember looking at a couple Roush's before I got my GT, and the Stage 1, which is just the body kit, some interior upgrades and mufflers added about $8,000 to the car!!!
Shoot, I could buy the body kit and stuff for less than that.
I'm a bang for the buck kinda guy. I'd rather buy a stock GT and customize it myself with whatever body kit and supercharger I wanted. That way it'd be a bit more unique and less expensive. The only drawback is not having the resale value that a Roush has.