The Screw,tap.,3x42 is the lowest priced item on this Taillight (nps508/9) schematic.
A sample from the products for the Taillight (nps508/9) include: Bolt,flange,6mm, Lens,taillight, Washer,chain Case, Packing,t-lt Lens.
The most expensive part in this assembly is the Unit,tail Light.