The component with the lowest price in the STARTER MOTOR schematic is the Nut,thin 6mm.
Parts such as the Starter Motor: Motor Assy.start, Flange,start Driv, O-ring,24.4x3.1, Gear,start Red are included in the Cb750sc Nighthawk 750 1983 (d) Usa Starter Motor parts fiche.
The Starter Motor is made up of components including this Motor,startor which is the most expensive.