The component with the lowest price in the FUEL TANK schematic is the Clip B8,tube.
Parts such as the Fuel Tank: Tank Set,f*nh138*, Cushion,fuel Tank, Clip B8,tube, Cock Assy.,fuel are included in the Z50jm Monkey Baja Japan Fuel Tank parts fiche.
In this schematic the "Cushion Fuel Tank" is used most often.