The Washer(6.5x18x1) is the cheapest item from this partsfiche.
The Rear Fender is made up of components including this Fender,rear which is the most expensive.
Parts such as the Rear Fender: Nut, Screw, Cushion, Washer are included in the Gs750b 1978 (c) Usa (e03) Rear Fender parts fiche.