I had a '95 SL for 4 years and put over 40k on it. I really miss that car, traded it for a Harley 4 months after I got my Camaro. Only things I had to replace were the usual pieces that break or wear down after 100k.
The carfax is very very important. A well maintained 3000GT will last quite awhile.
www.3si.org
That forum has everything you will ever need to know about 3000GT's.