The component with the lowest price in the CYLINDER HEAD schematic is the Circlip(1hx).
Some items from this specific schematic: Washer, Plate(3tj), Plug, Spark (r Cr9e), Guide, Intake Valve, Plug, Straight Screw(1hx).
The Cylinder Head is made up of components including this Cylinder Head Assy which is the most expensive.