The component with the lowest price in the CAMSHAFT/VALVE schematic is the Cotter,valve.
Some items from this specific schematic: Shim,tappet (2.65, Shim,tappet (1.82, Shim,tappet (2.50, Shim,tappet (2.67.
In this schematic the "Cotter,valve" is used most often.