Oldguyonoldbike

It's a Bafang conversion kit that I got from Greenergia, sold on Amazon. I'm not a big fan of Amazon, but I'm new to ebike conversions and I felt safer knowing Amazon's return policy. The kit included motor, on/off switch, thumb throttle and a light for $470. No instructions and practically no product information came with this. I then discovered Ebike Essentials, Bafang's US storefront with a decent website. I ordered the battery, a gear shift sensor that kills the motor during shifts, acting as a sort of clutch, a brake sensor that kills the motor while braking, and the speedometer/controller from them. An Australian shop called RevBike has some very good videos on the installation process. All in, I spent a little over $1000 for the system with a 500w motor and a 48v 12amp/hr battery with Samsung cells. That's more than I initially intended to spend, but I'm happy with the results in terms of power and expected battery life.
One could save hundreds of dollars by going with a smaller battery or a less powerful motor. There are also hub-mounted options, but the price difference is not great and I imagine that the mid-mount motor feels more natural and has less of an impact on handling.