I was thinking about getting one a while back and threw out the call for suggestions here. I wasn't looking specifically for a 'sports' car, but something more economical on gas than my Suburban that I could use as a daily driver (the kids have all moved out, so we don't need the 'bus' any more). Anyway, you might want to check out
this thread I started about the spitfire to see what some of those who have been down that road have to say

Needless to say, after reading some of the comments/suggestions and talking to others who have had the pleasure of owning one, I wound up getting a '73 VW which has so far been a blast to drive, super easy to work on, and very light on the wallet (even if it's not quite as 'sporty' as some of the other vehicles I was looking at)!
Cheers,
Brad