The normal recommendation is to steer away from cross drilled rotors, they tend to crack around the holes. The bottom of the range slotted rotors (I think DBA 650 is the right size for wrx with 4 pot fronts) should set you back around $150 or so each, 4000s will set you back a fair whack more, and unless you plan on tracking the car I personally dont think it will eb worth it, though other members do.
For around $60 you could pick up some whiteline camber pins as well, once again, some members wouldnt recommend them, but i have had them in my 323 for 8 months now with no problems. set your front wheels up with a few degrees of negative camber and you will notice a big difference in what it takes to make your car understeer
strut tower brace->
http://www.whiteline.com.au/docs/bulletins/095_ksbQ.pdf
as always, this is just my opinion, do some research and form your own opinion.