The Pin-cotter,2.0x15 is the lowest priced item on this Rear Master Cylinder schematic.
Parts such as the Rear Master Cylinder: Ring-snap,20.5mm, Piston-comp-brake, Cap-brake, Reservoir are included in the Kdx250-d3 1993 Al Rear Master Cylinder parts fiche.
The most expensive part in this assembly is the Cylinder-assy-master,.