The most expensive part in this assembly is the Camshaft.
Parts such as the Cam Shaft-valve: Bolt, Spring, Seat,valve Spring Exh Outer, Valve,exhaust are included in the Gsxr1100 1990 (l) (e01 E02 E04 15 16 17 18 21 22 24 25 34 39 53) Cam Shaft-valve parts fiche.
The Cotter Valve is the cheapest item from this partsfiche.