1. At $3500, you're looking at mint, rust free--the car better be just that.
2. It's a toss up with reliability. If the 900 is as well maintained as advertised, you'd likely have more headaches with a $3500 used 9-3 or 9-5. On the other hand, you can also get a pretty nice 9-3 for that money.
3. Require service records. Without them, walk away unless you've got someone showing you every area of the car on a lift. These cars can be serious money pits (ask me how I know).
All in all, what's the reason you're getting the car? For the wife to drive? If that's the case (and you want to stay married), I'd probably opt for something else other than a 17 year old c900.
2. It's a toss up with reliability. If the 900 is as well maintained as advertised, you'd likely have more headaches with a $3500 used 9-3 or 9-5. On the other hand, you can also get a pretty nice 9-3 for that money.
3. Require service records. Without them, walk away unless you've got someone showing you every area of the car on a lift. These cars can be serious money pits (ask me how I know).
All in all, what's the reason you're getting the car? For the wife to drive? If that's the case (and you want to stay married), I'd probably opt for something else other than a 17 year old c900.