tl;dr: Ever used one of those "new mouse" feature test / demo applications? If you did it with a 5-button mouse, you've already figured out how to make your own one-handed chording keyboard. Also, the patent(s) are probably unenforceable.
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I just quickly did this to visualize the poll responses.
https://www.meta-chart.com/share/how-much-would-people-pay-f...
Personally my bid is in the $50 slice, because I see this as a deconstructed / reconfigured 5-button mouse without the laser (or ball if you are more of a retro sort). Even a regular 5-button mouse driver would be able to read it correctly without modification to the code - you are only concerned with interpreting the input and writing the output at this point.
In a pinch, and for dev purposes, you could probably get away with experimenting just by putting tape over the laser sensor (or remove the ball if you're that retro guy) and then writing the interpreting chord combinations until you decide build it into a prettier, and less likely to give you CTS, form factor.
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As to the patent, lest we forget devices like this one have existed for decades already using the one-handed-gravity claim extensively: https://www.youtube.com/watch?v=j2Qh5bHtHMY
There probably is some novelty in what he's come up with, but absolutely everything about it appears to have prior art. Unless my implementation idea is missing something.
Maybe he could patent some parts of the form. But then I think every company working in VR would immediately take issue. A VR paddle with 5 keys is exactly this guy's patent(s) if you ignore all the bells and whistles like spacial sensors. A wireless 5-button mouse already squashes that part of the patent.
> He's invented a 5-button mouse without a sense of direction!
I'm certainly open to discussion on this because I think OP has a really interesting question, and I'm a little surprised that there is so little commercial attention. Is there a chording machine monopoly not yet mentioned here?