Kitchenaid Dishwasher Pump Motor Repair - Not Cleaning Dishes

Model Number: KDTE404DSP0
Brand: KitchenAid
Age: 1-5 years

I was told my Kitchenaid Dishwasher needs a new pump motor because the arms are not spinning and thus the dishes are not getting clean. I was quoted at $400 for this Repair. I called Kitchenaid and learned the part costs $160. Does this seem reasonable? Is this something I can do myself or a handyman can do? The dishwasher is only 3 years old but I think $400 is around 50% of the value of the appliance when we bought it which seems really high.