The U.S. got about 50 Elise Sports. One of my track friends (and a driving instructor) has one. I've never seen anyone keep up with him at track weekends. I would still add a Cooper S to the list. Easy to acquire in the OP's budget, very quick, excellent handling, very forgiving, and a blast to drive.Trouble is we didn't (really) get the S1 in the States (I'm assuming he's in the States since he said "$" and wasn't specific). Shame... I'd kill for an S1 Exige or one of the pre-Exige S1 Elise Sports.
S2000
Miata (1st or 2nd gen)
WRX/STi
Evo
Check insurance first, of course.
Sadly, our home track (Gateway International Raceway, Madison, IL) just shuttered its doors last week. Between that, and my insurance company writing in a clause to exclude HPDEs, my track days may be done for a while.