1994 Saab 900???

I've owned a '95 and a '97. Which engine is in the one you're looking at? '94s had more problems than the other years, probably due to being the first year of the GM900. The 2.5 V6 probably had the most problems of all of the available engines (lucky for you, the V6 was intended for the US market, so they are rare in Europe). The problems with the V6 were mostly due to its adaptation to the car. It is actually a good motor (a Vauxhall motor), but it had some typical electrical problems and a chronic issue with bad timing belt tensioners. My '95 had the V6, and my '97 had the 2.0 Turbo. The 2.0 Turbo is a very reliable motor, and the naturally aspirated 2.3 is pretty good too.

 

This is where you'll get best overview.
http://www.saabcentral.com/features/gm900_93_index.php

Tons of resources regarding this model on that page - including second-hand buyer's guide.

That's without even tapping into the forums.

 

Munki's buyer's guide is an excellent resource. It's linked on that page.