I've been toying with the idea of putting an intake on, for the sole purpose of hearing the BPV because I think it's a cool sound, regardless of what people say about intakes on the 08/09! I think the exhaust will be first though.
Oh and as far as the SPT exhaust goes, you can get it here for $530 shipped.
SPT Cat-Back Exhaust for the 2008 WRX (5-door)
If you're going to be paying full price for the SPT (~800) I would consider looking at the Cobb, since you can then drop in their DP to match if you get to that point. But at 500 bucks, the SPT isn't a bad deal. It only seems that way since some people got them for 300