I'm curious - where did you come up with your $75k cost for retrofitting existing vehicles?
Additionally maximizing profit (and this may read as condescending but I do not intend for it to be so) does not necessarily mean maximizing price. Obviously if you are not selling at a loss you can potentially make more money with a cheaper price point on volume.
I do agree, however, that first adopters will likely pay a premium.
Eventually I imagine insurance companies will help subsidize these things too - if the price does not become trivial.