The most reasonably priced component used on the Xr250 1980 (a) Usa Seat is the Bolt,flange, 8x20.
The Seat assembly is constructed from several parts from which the Seat Assy. is the most expensive.
Parts such as the Seat: Bolt,special,6mm, Bolt,flange, 8x20, Mark, Bolt,flange,6x10 are included in the Xr250 1980 (a) Usa Seat parts fiche.