The component with the lowest price in the TRANSMISSION schematic is the Circlip-type-c,20mm.
Check out any of the twenty Transmission components enlisted.
Parts such as the Transmission: Gear,input 3rd&4th,18, Shaft-transmission In, Collar,sprocket, Gear,input 5th,19t are included in the Kx250-n1 2004 Europe Transmission parts fiche.