Some items from this specific schematic: Bolt,recessed,5x1, Chamber Comp,exp, Bolt^wash.,sh,6x1, Bolt,flange,sh,6x25.
The lowest price component in this Expansion Chamber (ed,u) parts-list fiche is the Bolt,recessed,5x1.
The Expansion Chamber (ed,u) is made up of components including this Chamber Comp,exp which is the most expensive.