A lot of local Subie heads hang out at www.spooledupracing.com

The site owner (Dave Hensler? not sure on last name) also gives awesome deals on new import parts.  He's my first stop whenever I need something that is stock, and new.  He also autocrosses with our club, although not lately.  Used to race a 2nd gen RX7 with us, but now has a WRX that he's getting ready.  You won't find cheaper prices, and he provides good customer service.  I'd check with him first, even if you are looking for used stuff.

Good luck. :)