My research led me down the rabbit-hole of building my own EBike.
I picked the Schwinn Boundary as the foundation for this project...which is a bike that can be had at Wal-Mart for under $300....the Boundary bike is largely crap, but the the FRAME is very capable with good geometry. I used the BBS02, and paired it with a 14A/h battery.
I plan to VLOG the whole experience building it, but in the meantime, I need to tally up final costs...which is not easy. There are costs in essential upgrades, and there are costs in non-essential upgrades (such as for aesthetics, like hand grips).
I essentially replaced everything on the bike with the exception of frame and wheelset.
...and now i have already started on my second conversion.
That's the way to do it Basic hardtail mountain bike frame and wheels and everything else is replaceable and upgradeable. Great job!