Parts such as the Headlight: Screw-washer,5mm, Base Comp. Positi, Bulb,headlight, Rubber P/light are included in the Vtr1000f Firestorm 1997 (v) European Direct Sales Headlight parts fiche.
On this parts fiche the Screw-washer,5mm is the most specified component.
The component with the lowest price in the HEADLIGHT schematic is the Screw,tapping,4x12.