The component with the lowest price in the SEAT schematic is the Nut,flanged,lock,8mm.
Parts such as the Seat: Seat-assy,back,gray, Belt-seat,buckle, Cover,seat,back, Belt-seat,latch Plate are included in the Kaf620-a3 Mule2510 1997 Europe Seat parts fiche.
On this parts fiche the Nut,flanged,lock,8mm is the most specified component.