On this parts fiche the Band A, Tube is the most specified component.
The component with the lowest price in the AIR CLEANER schematic is the Bolt,hex., 6x16.
Parts such as the Air Cleaner: Seal,elmt.cover, Washer,plain, 6mm, Piece,air Cleaner, Element,air/c are included in the Cb550k3 Four France Air Cleaner parts fiche.