Ok, I will chime in with 2 cents.
I would go against the norm here and suggest that you buy a 1998 Lincoln LSC. First, the car has more luxury than just about any other vehicle. Second, you can pick up a low mileage original car, for around 3500. Yes......3500. Using very limited bolt ons, the car will do 13's as the car originally came with the Cobra engine. Not fast enough? They make a supercharger for the car that you can slap on. After that, you have a car that does in the 11's and will beat most Vipers.
In 1998, the only American cars that came with totally independent suspension were the Corvette, the Viper and yes, the Lincoln LSC. The car also has an air ride suspension that really smooths out the bumps.
And the cost to get a supercharged LSC with low mileage? About 7,000 out the door. And rock solid.
Don't believe me? Hot Rod magazine just had an article about how good the deals are on the Mark VIII, how stout the engines are, and what a great deal it is.
Lastly, the car is built in America. For what some people spend on trinkets or tires or something else, you cannot go wrong. Even if you hate the car or it blows up after you bought it, you can sell off the wheels and tires and still not be that much in the hole.
Check out the following boards for further information. Almost as good as the Viper Club.
http://www.lincolnvscadillac.com/forumdisplay.php?f=6
Oh, and the car gets 30 mpg right out of the box. Can't go wrong there either.