Yea, they're not hard to come by - there are several specialists in the UK alone. Excellent club support too.
You could get an immaculate six-speed one for well under your budget - but finding the right car (colour-wise) for you could take some time. It is, obviously, a much older car though - You'd be looking for a '95 or '96, although at that price it should only have done about 40,000-50,000 miles.
I used to average around 24mpg in mine, in daily use - but that was an automatic. On longer runs it was up to and over 30mpg (70mph = 1800rpm, haha), though. Manual ones are usually 2-3mpg more efficient but obviously drive them harder and that'll fall.
Averaging 25mpg isn't much these days, though, and you might find it tiring visiting the pumps often (much like with the 350Z or Boxter) - although the Corvette does have a wallet-alarming 90 litre tank, which'll keep it motoring for a while.......Brimmed, anyone?
They all have electric leather seats, cruise, climate control, ABS, PAS, an LSD, front and rear discs, electric windows and mirrors, adjustable steering column (rise and reach), remote central locking, various additional instrumentation and full trip computer facilities, and some have electronically adjustable suspension - amongst other things.
One benefit is that although there are several specialists around who are set up to deal with them, regular maintenance is very simple - so a decent local garage can keep it ticking along without any issue. There are no complicated cambelts to deal with, for example
Obviously you don't walk into the purchase of something like this, or any of the above, without doing some homework (like seeing if you do have any decent local independant performance garages, or seeing what maximum and minimum economy you could get away with) - but I find the C4 Corvette always an interesting, and sometimes suprisingly realistic, alternative
All C4s have targa tops (the roof panel just unbolts and slides into the boot space) but they do a convertible as well:
http://www.corvetteclub.org.uk/viewtopic.php?t=9094
Like that.