Yeah, just have a look at the For Sale section.
The price differences are quite a bit.
If you fancy a brake upgrade, start with:
New brake pads / Slotted rotors / HEL Metal Braided Brake Lines / Brake Master Cylinder Stopper.
If you still want Brembo Calipers, I believe the R32 GTR V-Spec / V-Spec II and R33 GTR calipers are all interchangeable.
Re-build the calipers and do what I listed above, but obviously buy the Pads and Rotors for Brembo size calipers.
Yes prices are in AUS Dollars