I have a 2006 9-3 2.0T, the only issues I have had are the GM parts (fuel pump, etc), it has not been as reliable as our other two Saabs are/were but not terrible. As noted earlier it is a Ecotech GM engine that has been redesigned (only the block is the same). The car is based on the same platform as the Malibu. Most of the Ecotech sensors etc. are off the shelf GM but you may need to swap a connector on the odd one (coils are not, more on this later). Upside, it drives great, handles great, good gas mileage (usually mid 7l/100km), and goes like stink.
We still have a 2002 9-5 2.3t which has a Saab engine, not a GM engine like above. For a 14 year old car it has been very good to us (we have had it for 11 years). Some minor wear items etc. We replaced a 2000 9-3 2.0t with the current 9-3, I miss the hatch, this car was very reliable but the clutch was going at 300,000 and the rust was getting bad. If it wasn't for the rust I would have replaced the clutch and kept it.
As for parts, lots of parts are shared with the GM family so they are not that bad. Ignition coils are pricey because only the original Saab ones work right. The motor fires the plugs in the off cycle as a way to measure knock (there is no knock sensor on a T7 or T8 Saab--pretty much everything after 2000) so correct coils and plugs are critical--they are the knock sensors, I just pick up some good used coil packs and keep a spare just in case. You need to know how they work or your mechanic does, one example: put in the wrong plugs and you can blow the engine, throws off the knock sensing and too much boost and boom. The local wrench does not know these things and it adds to the bad reputation...
In the end our three cars have been way cheaper to drive and maintain than everyone I know who has or had a BMW, Volvo, Audi, or Benz. All three are/were manuals and Saabs are easy to find in a manual.
The first question I ask when buying one is where was it serviced. If they say one of the local respected Saab guys (GB Auto, Aktive, Beacon, etc.) I keep looking at the car. If they say the local whatever, I run away.