Subaru does not offer a hitch specifically for the WRX/STI, I have been suggesting www.etrailer.com
as they have options for the turbo models. The side vent is no longer available painted unfortunately.
Side Nets - $33.00
RH Vent - $24.42
Both pieces are special order, two days to receive. If you can find a painter locally you could try a paint kit from an online retailer such as www.paintworldinc.com
which is often very good for small pieces. It may be harder for this white color though, people have told me that it is tough to match. You could also check with IAG, they now have a body shop and handle many Subaru's.