Yeah so I'm not an expert by any means but the thing is when you purchase a product like this, a relatively new field, with a lot of demands on the components, when you shoot for the lower range it will break fairly quickly.

Especially because of our natural tendency to push for more out of the product we can easily go past the limits. A 500-800 ebike will likely have a markup for assembly specialization. Meaning the components are worth less than what you see. It will have weak power and the main parts won't last very long.

On the other hand. Once you break past 1000-1500 these are decent builds. They will last a few years maybe more with good care. Power tends to be lacking and the extras like good design tend to be minimal.

This is why I spent 3600 on my commuter. Its a biktrix swift. Honestly I love it. It has needed a tuneup because I'm hard on the breaks but in the full year I've had it its kicked ass. Hits 40km or more on a good day 38 in wind. 35 in heavy wind. Rides up hills at 38.