Parts such as the Taillight: Bolt, Nut, Flange(4mv), Nut, Lens, Flasher 2 are included in the Cw50 1998 4vvh Portugal 284vv-353e1 Taillight parts fiche.
The Nut, Flange(4mv) is the lowest priced item on this Taillight schematic.
The Taillight assembly is constructed from several parts from which the Base Assy is the most expensive.