This is why its important to keep innovating in any way we can.
Even though controlling this things with a smartphone might be cool, the best will be to control them with our own brain, which should be very common in the years to come.
And I have no doubt that the costs of this technology will decrease with time, so everyone that is in need of this, will be able to afford it. Its like everything else, at the beginning it is quite expensive, but then the price is reduced and more people is able to buy the product.
Thanks for your comment, in time we can hope that mind controlled prosthesis become common real soon, as it would make it alot easier for amputees to go about their normal lives