Last time I checked (about 1-2 yrs ago):
brembo - RM4000++
seats only - RM5000++
complete front b/kit for e6 (ori) - RM5500++
my humble suggestion:
If budget is no issue - go for the ori stuffs. if not, get the complete fibrekit for the body parts (now available for all evos). Forget bout the seats and door panels - get racing bucket seats - e.g. sparco. will cost you less than the ori seats. Paint the car white and call it the RS.