All of my first cars were c900's. I loved them. Then, over about 10 years, I moved on to a few 9000 Aeros, a few OG 9-3's, 99 viggen, and 03 9-5 Aero. After all of those, I spent about 6 months last year (summer/fall) in my SPG, driving a few days a week in it.
While I still loved the car (particularly the looks of it), it was a HUGE adjustment going from more refined, newer saabs/cars, back to a c900. The ride quality, utility, # of creature comforts, needed maintenance, etc, were all annoyances that I could never have dealt with if the car was my full-time daily driver. With that being said though, it's probably a totally different story if the car you're looking at is well-sorted, has AC, updated maintenance, etc. Beyond that, I'd say: c900 = summer car, not daily driver, unless you're conditioned to love the things that make the car the unique driver it is.
If I were looking for a cheap Saab daily driver, I'd go with the following priority:
1. 9-3 sports sedan 03+, they are awesome cars. $3000 gets you a nicer earlier one
2. 99-02 9-3 4dr hatch, more reliable than a 9-5, more room, etc. These are all over for $1500-2500.
3. 9000…awesome cars, not usually maintenance whores, but hard to find nice ones
4. 9-5. Pretty decent overall cars, good ride quality, but engine failure = undeniably worrying issue.