Some items from this specific schematic: Washer,9x28x2.3, Cap-assy-tank,fuel, Screw, Tank-comp-fuel.
The component with the lowest price in the Fuel Tank(CN,US) schematic is the Bolt-flanged,8x30.
The sub assemblies and components that make up this Fuel Tank(cn,us) include this Tank-comp-fuel, the most expensive part.