The component with the lowest price in the OIL PUMP schematic is the Screw.
The twenty-two Rg500c 1987 (h) (e01 E02 E04 E06 E15 16 17 21 22 24 25 34 39 53) Oil Pump component parts are all listed in this schematic.
This Pump Assy,oil is the most expensive of the items that make up this Oil Pump assembly.