Welcome aboard... if u can find a 95 in your price range, pick it up ... seriously!!
93' or better have the limited slip differential, and alot of the minor factory problems were fixed. As far as modding up an mr2 turbo, there is alot of potential for these cars, and I will give a link to a great site, which has also been posted on this forum, but instead of making u look for it, I will post it here. Basically, u can get 300 HP at the flywheel which is a 50% gain over the factory for 1,000 to 1500.00. Past that point u are looking into a little more money and a little bit of a pain in the butt...
As far as the mileage is concerned... it is unlikely that u will find a car that is over ten years old with fewer than 100,000 miles on it. Just remember that this is a toyota after all, and one of the more reliable sportscars u can but.... And I have had the pleasure to say that and know it is the truth.
Some cars will have a new engine, or tranny, but the mileage on the car is still going to be the same. Good luck and hope to hear from u soon... : Brian
http://www.mrcontrols.com/primers/power.htm