It's probably hard for ebikeling to compute in the small 500w motor market with similar offerings from chinese vendors at a lower price. That would explain these super big motors.

My origiinal ebike conversion will be a 500W 36V rear hub ebikeling kit that will be 10 years old this summer, I [aid about $220 USD for it, but the price dropped quick, as my second one was about $175 a year or two later.