The component with the lowest price in the LEFT CRANKCASE COVER/ GENERATOR schematic is the Socket,bolt,6x32.
Parts such as the Left Crankcase Cover/ Generator: Bolt,flange,12x48, Washer,thrust,30x, O-ring,13.8x2.5, Cap,14mm are included in the Xl600v Transalp 1991 (m) France / Yb Left Crankcase Cover/ Generator parts fiche.
Of all the components used in this assembly the Generator Assy.,f is the most expensive.