The Washer,plain, 6mm is the lowest priced item on this Lower Crankcase schematic.
Some items from this specific schematic: Bolt,hex 8x97, Bolt,hex 6x45, Crankcase (lower), Crankcase (lower).
The Cb350k0 Super Sport England Lower Crankcase consists of eighteen pieces with the Crankcase (lower) being the most expensive.