...I don't know about you but I wouldn't buy anything named after a computer file extension....lol
I personally like Eclipses, though you could probably get a NICE used firebird formula, trans am, camaro, ss, etc... for under 20k. They will be a few years old (like 2-5) but even the really new used ones should be under 20k. There was a nice TransAm in the paper last year that my dad was looking at. It was a 2000, this was mid 2001, cost was 17k. Car had everything, was a vert, leather, the new ones have factory 500watt systems, 305-320ish hp, will smoke most/all stockish mustangs (besides the new 2003 SC Cobra...but that's a different beast).
If you want to go the import rout though...like i said I like eclipses, other than that acura integras (used of course...hint: TypeR)....
Or save your cash and get a 2003 C5 Corvette Z06.....hum....maybe that's a little out of reach.