Sourcing parts for commercial airplanes is a whole different animal than sourcing parts for our cars. In my career quickly I learned that money was not the most important issue if an airplane is AOG. Time is by far the most important factor. It would be a huge mistake to wait for a cheaper part.
Get it fast, get the airplane back in service, and nobody ever complained about price. Price of parts was discussed as a point of general interest, but that's all.
For reference, an autopilot or navigation computer that is about the size of two loaves of bread could cost a few hundred thousand dollars. If you need one, you need one. Nobody bats an eye.
That's to purchase a new one but they get repaired for much less.