Parts such as the Seat: Seat-assy,low Height,, Bolt,6x20, Seat-assy,high Height are included in the Kx250-h1 1990 Europe Uk Al As Seat parts fiche.
The component with the lowest price in the SEAT schematic is the Bolt,6x20.
In this schematic the "Bolt,6x20" is used most often.