The component with the lowest price in the REAR WHEEL schematic is the Pin.
A sample from the products for the Rear Wheel include: Spring,brake Shoe, O Ring(d:2.4,id:9.8), Sprocket,rr(33t-428), Tire(2.50 10).
The Rear Wheel assembly is constructed from several parts from which the Hub,rr Wheel is the most expensive.