Check out any of the eleven Seat components enlisted.
The component with the lowest price in the SEAT schematic is the Nut,flange,6mm.
Parts such as the Seat: Bolt,flange,8x16, Bolt,hex,cap 6x16, Seat,assy Rear, Stay A,rear Seat are included in the Vt1100c2 Shadow 1999 (x) Australia / Kph Seat parts fiche.