The component with the lowest price in the CARBURETOR PARTS schematic is the Screw-pan-cros.
thirty-three components are shown in this En450a5 454ltd 1989 Usa California Canada Carburetor Parts exploded diagram.
Some items from this specific schematic: Jet-needle,01b38, Main Jet,2nd #128, Clip, Float Valve, Screw-pilot Air.