You can get an '02 Camaro SS for under $10,000 if you shop around. It'll beat any production mustang ever built (excluding those limited production runs that cost more than a Z06 vette) on a track and will beat any mustang under $50,000 on the dragstrip. It handles better than any mustang, gets better gas mileage, goes faster, has a bulletproof engine, and can be modded with minimal effort to go MUCH faster for not much money, and it'll still be more drivable than a mustang that costs 5 or 6 times as much.
As Grayeagle says though, for an American sports car you can't beat a vette. Even a used vette is going to drive better than any other new American car built today, from a performance perspective.
If you want some REAL fun though, get a used miata and pay a speed shop to drop a V8 or supercharger into it. There is one shop that is pushing 200mph in a miata and it still weighs less than a vette and handles about as good. I think "monster miata" started the trend by dropping the old 5.0L mustang engine into a miata, but there are a few places doing the mods now with lots of interesting options. You can start with a $6000 miata and $15k later have a sleeper that will suck the doors off of Grayeagle's vette. Of course, the miata will probably redline around 150mph because the mazda engineers have confirmed that the miata simply isn't stable above about 140-150 so the speed shops usually won't gear them tall enough to go any faster than that. My Dad considered a V8 mod for his miata (he has both a 10th anniversary miata and a beautiful electric blue Z06 vette) but he settled on a $4,000 supercharger package that merely doubled the miata's power while grossly fattening the usable torque curve. It used to be really fun to drive, now it's really fun to drive and FAST.
