The price is whatever people are willing to pay. It seems that enough people feel the price of the i3 is reasonable enough as it has met BMW's sales goals. In the first couple of years, they had a backlog, and had to expand the production capacity, and, as far as I know, they haven't shut down production from lack of demand.
If there were another vehicle that was similar enough, people would abandon it or not buy it in the first place.
One of the hassles to any EV sale is the dealerships...because there isn't as much service required, and they must spend money on training and special tools to service the i3, not all of them have much incentive to sell them as a lot of income comes from the service department, and the i3 doesn't generate a huge amount, at least so far. No idea what the dealer margin is on an i3 verses say one of their ICE vehicles.
2011 535i x-drive GT, 2014 i3 BEV