As someone who's been longboarding for years (including commute), I would be interested in something that:
* Would let me ride normally, without using the motor at all (e.g. gear in neutral).
* Would recharge going down hill.
* Would assist me going up a steep hill.
My current board is 40+ inch Arbour board that I got for around $200 5-6 years ago. Every couple of years, I spend ~$40 on new barings (too lazy to maintain).
I don't actually want an electric board most of the time, as it's one of few sources of exercise for me, but it'd be nice to have an assist going up hill.
Not sure I'd spend more than $400-$500 though.