[N1 (Mirko)]

You could prossibly do it yourself. My wife needed something to get her to work and back without reducing physical exercise to zero, so we got a 2nd hand 26" Giant, a Bafang 350W mid drive conversion kit from AliExpress and some sundry parts like mudguards and put it together in a few hours. You basically replace the crank set, install the battery, cables and a couple of sensors and keep everything else. Cost for the whole thing was around $1.2k at the time, incl. the donor bike. It went together pretty easily, and most of the work was in attaching the battery properly and tidying up the cables. Attached photos of the build in working order but before the cable work was cleaned up a bit. It's now done 6,000km and has not needed anything beyond the usual wear-and-tear items. It's an ugly bast*rd but is robust, reliable and has more than paid for itself.