The component with the lowest price in the SEAT / CARRIER / TOOLS schematic is the Bolt,hex., 6x16.
Parts such as the Seat / Carrier / Tools: Bolt,hex.,6x16, Bag,tool, Wrench 21,box, Bolt,hex.,6x16 are included in the Pa50i Hobbit 1978 Usa / 20mph Seat / Carrier / Tools parts fiche.