The component with the lowest price in the Rear Master Cylinder schematic is the Bolt-flanged-small,6x.
Some items from this specific schematic: Hose-brake,rr, Washer,8.5x13x1, Pin, Bolt-flanged-small,6x.
The Rear Master Cylinder is made up of components including this Cylinder-assy-master, which is the most expensive.