It would be possible to do this sort of thing on the cheap with a lower price hub with fewer gears. For my commute three or four speed would work- get a suitable frame with disk mounts (and clearance for fat tyres in the winter in my case). I've certainly thought about it.
Having said that I don't see derailleurs as being high maintenance, simple (say) 8 spd setup on down tube shifters, single chainring up front, just keeps working with minimal attention- usual chain maintenance and lube pivots at intervals- and parts are cheap (I bought a- rather grimy- 105 8 speed mech for a penny on
eBay once and had it on my commuter for two years). Hubs and enclosed chain (with stub axle wheel mount for easy puncture fixing) would improve matters but not many options there at the moment.