Youre right, even in New England, theyre not seen all that much. Though IMO parts are a bit harder to find at the wholesale online OE parts distributors, as compared to MB and BMW, I have found that dealerships are much more fair in their pricing structure, especially if youre buying parts to DIY. For example, they sold me a Mobil 1 0w-40 6-qt box, and oil filter and orings, etc., for less than Id be able to get just the oil for at wal mart!
If you go with a 4-cylinder model, maintenance should be relatively easy... Maybe BMW I-6 engines are easy to work on (the I4 in my 91 BMW E30 318i is), but the v6 engines in most cars are likely annoying and harder to access.
Another benefit is all-weather performance. Though my old 83 MB RWD turbodiesel was excellent in snow, most RWD vehicles arent. My BMW certainly isnt, and is but marginal with snow tires. SAAB designs excellent all-weather, snow-beating vehicles. I got a set of snow tires for my 9-3 (OE 16" wheels, same as what came on my car and goodyear eagle ultragrip tires from Europe, all for $750 at the dealer), but in reality, I drove through some storms with the OE tires on my 9-3, and the car did great! I was pleasantly suprised!
One last thing to consider is that historically, SAAB hasnt held resale value very well... Irrelevant if you buy your car and plan to keep it for a LONG time, or if you buy in the secondary market. As you appear to be going to do the latter, youll have an easy time finding a good deal, IMO. And, after all, good deal + good MPG + good safety = top notch car!
Good luck, and keep us posted as to what you decide!
JMH