I'm curious if Amazon's charger setup will be different than your normal charging setup. Presumably, you want to charge while the vehicle is being loaded so you want the chargers spaced out around the loading bays. (This nice tour video suggests that things may not be as efficient as I thought: https://www.youtube.com/watch?v=r6lO2_2tyfY)

Those $500 chargers are the at home chargers. I suspect that Amazon would want a more expensive charger that handles higher power to get more energy on-board during a short loading period. As someone else mentioned, the distribution infra is also quite a bit of money.