Out of thin air. Why would it be cheaper? If you made the product, would you try to maximize profit or do it for SAFETY and the good of society?
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.