It seems like the Subaru's of the same age go for a lot more money. Maybe due to Saab no longer selling cars & Subaru's seem to keep their value better than other cars due to the loyal following.
On autotrader right now.
05-06 Subaru WRX, manual, anywhere in the country. 34 cars.
Highest Price:$18,991
Lowest Price:$8,500
Average Price:$14,685
05-06 Saab 9-2x Aero (turbo=same as WRX), manual, anywhere in the country. 6 cars.
Highest Price:$12,995
Lowest Price:$9,250
Average Price:$10,910
One thing to note is that even though I searched for 05-06, there were no 06 Saab's since there was such a low amount made and I'm sure they are the most sought after variation (due to 2.5L engine).
Searching for WRX 05 only. 15 cars
Highest Price:$17,995
Lowest Price:$8,995
Average Price:$13,606