The answer is more complex than the answers that have been offered to this date.
Some manufactures have product specific compoenents (Original equipment parts) Or OEM Parts that are specified by the design Engineer and are only acquired from that manufacture and then through an authorized Dealer or Servicer. If the equipment is designed to address higher efficiencies or specific Static pressures you will see higher cost in replacing these compoenents. Variable speed blowers incorporate a motor and motor module allowing a variation in the amount of air moving throught the structure at any given time. This capability addresses Efficiency and comfort of balanced temps throughout the Home or buisness. These become very exspensive to replace.
For any motor replacement the capacitor should always be replaced as the stresses that caused the motor to fail have also stressed the capacitor and even if it tests good at the time of replacement of the motor, the capacitor may fail at any time and damage the new motor compoenent.
My company is one of the largest TRANE Dealers in the nation and we use the same pricing structure as New Car service centers.
Example: If you take your car to a Authorized repair Center the Repair person will give you a price of the repair,parts and labor combined.
The (2) parts of this pricing structure is Parts and Labor.
Parts are costed at a competitive rate for what ever market your in.
Example: The cost of a compoenent is not the same on the East or West Coasts or North or South,but driven by vender and delivery costs.
Labor is figured on a National average , this rate will be relitively close in all areas with some diviation.
Parts + Labor = Cost to customer.
My Technicians are paid from the labor portion of this calculation and make no commision for selling compoenents.
If a quoted repair pays the Technician 1hr labor and it takes the Tech 3hrs the customer pays no more than the original repair quote.