Some items from this specific schematic: Cotter Valve, Shaft,vlv Rocker Arm Exh(l:76), Bolt 6x30, Arm,valve Rocker,exhaust.
Of all the components used in this assembly the Camshaft is the most expensive.
The most reasonably priced component used on the Dr250s 1983 (d) Cam Shaft - Valve is the Pin.