A bit late to this thread. Pick up an 06 GT Premium with 23K this Saturday. Supercharger and full exhaust (long tubes etc.) Tune, Intake and some other goodies as well as wheels and Nitto drag radials. $14K. I think you did just fine at $12,500.
So $450 with GT500 Brembos and Stop tech rotors. So for S197 I would just need the backing plates and stainless lines are the other thing the kit usually comes with. Sound about right.