I bought a mk2 mx5 a couple of months ago to have a go at drifting.
Paid £800 off ebay with 12mths tax 6 mths tax with 80,000 on the clock.
Insured it a couple of days ago for £600 so all in it comes in under your budget.
It's light, nible, loves to go sideways and everything works!
I looked round for a while and anything with a name to it came at a price...