Some items from this specific schematic: Case,upr, Nut, Washer(6.5x20x1.6), Speedometer (mile/kilo).
Of all the components used in this assembly the Tachometer is the most expensive.
The component with the lowest price in the SPEEDOMETER (MODEL S) schematic is the Bulb(12v3.4w,t10,bf175-01450a).