GRT beat me to the 3SI site. If the car is a VR4 I would get a carfax report and if possible have one of the guys on 3SI check the car out if they're in your area... they know what to look for and can warn you if they see anything wrong.
If it's a Base or SL model then you're probably in much better shape. There's a couple out there with over 250,000 miles on them and no major problems. My car has about 83,000 miles now and it's an automatic. The 5 speed base/SL models are probably the most reliable... followed by the automatics... then the VR4s.
Just remember that you'll either have to do the 60K maintenance when you buy the car... or at 120K miles if the current owner did the 60K on time. It's expensive though. Expect to pay $1200 for it. (Timing belt, pulleys, belts, plugs, wires, water pump, etc.)
FYI:
91-96 Base model 3000GT - 222HP DOHC - 5 speed or automatic
97-99 Base model 3000GT - 167HP SOHC - 5 speed or automatic
91-99 SL model 3000GT - 222HP DOHC - 5 speed or automatic
91-93 VR4 - 300HP Twin Turbo DOHC - 5 speed
94-99 VR4 - 320HP Twin Turbo DOHC - 6 speed
Jngrbrdman - The only version I would consider a collectors car would be a 95-96 VR4 Spyder hard top convertible.
The rest of the 3000GTs/Dodge Stealths are rare... but I don't know if they're THAT rare.
