Amusingly the problems you mention are inherent to a two-wheeler, and given the necessary dimensions of the egg-shaped outside you might as well add some more wheels at the corners to solve the stability problem. Then you end up with something like Renault Twizy [0] (look at the top view on page 2 to get an idea of its dimensions), currently sold today starting at 7000€, plus 50€/month of battery rent.
I would not have bet on that vehicle but it seems to be selling, since I already encountered a bunch of them.
A bunch of stats (for the topmost model, as the lower one is limited in power and does not require a driving license):
13kW/17ch
80km/h top speed
0-45km/h in 6.1s
100km range
6.1kWh battery
473kg with battery (~100kg)
[0] http://www.renault.fr/media/e-brochures/att00409285/ebrochur...