The component with the lowest price in the REAR ARM schematic is the Screw, With Washer(8v8).
This Rear Arm Comp. is the most expensive of the items that make up this Rear Arm assembly.
Some items from this specific schematic: Cover, Thrust 2, Washer, Plate (447), Bearing, Cylindrical(3gm), Screw, With Washer(8v8).