The most expensive part in this assembly is the Cover, Clutch.
The most reasonably priced component used on the Gp125 1981 (x) (e02 E04 E17 E18 E21 E22 E41) Crankcase Cover is the Gasket(6.2x11x1) (nas).
Parts such as the Crankcase Cover: Cover, Engine Sprocket, Screw (6x35), Screw, Washer are included in the Gp125 1981 (x) (e02 E04 E17 E18 E21 E22 E41) Crankcase Cover parts fiche.