Some items from this specific schematic: Packing,piston (nas), Breather-brake, Boot,caliper, Caliper-assy,rr.
The Rear Brake is made up of components including this Caliper-assy,rr which is the most expensive.
The most reasonably priced component used on the Zx750a3 Gpz750 1985 Usa California Canada Rear Brake is the Cap-breather.