What's a reasonable budget for an Amazon e-bike that actually lasts?

Across r/ebikes discussions, the recurring caution is that sub-$700 e-bikes can ride well out of the box but become difficult to service when proprietary controllers, displays, or batteries fail. Reviewers consistently advise budgeting at least $500–$900 for a known-brand commuter and stocking spare brake pads, tubes, and tires from day one.