That's why I offered it as a negative example how it should not be done, and what can go wrong.
The Joystick/HOTAS systems my SC orgmates discuss about go at least in the hundreds, and "gaming cockpits" also show up as popular now and then, which go into the thousands easily. For an optional system there would still be a market. It may even lower in price if more widely deployed, though I kinda doubt that sort of logic still works nowadays. Certainly, it is a more demanding technology, but there is still a considerable market even at that price. People who care for a "novel" experience like this would also have the hardware to use a VR system. And the hardware will get cheaper with time, nobody would pay top dollar for the GeForce 660 I still run (which is enough for my tastes), even though it was not cheap when I bought it.
AR systems are an unknown cost-wise, Some currently offered range from 220 for one that looks like normal glasses (220 is the price of a slightly upscale titanflex frame as well, though I very much doubt AR glasses can be ordered with corrective lenses at this point) to 900 and above for blockier and more powerful devices, with some models in-between. It's unclear what level of detail any of those can provide, and like for VR I have no idea how difficult they would be to integrate on the software end, or what additional technology would be required to actually interact with the projection in the manner I described initially.
As this is still very much an emerging technology, it stands to see how it will pan out short-term, anyway. I see some chance for its long-term adoption, as the industry is pushing games into compatibility quite a lot, but this phase where the interest is high is quite cruicial.