“The paper doesn’t directly address the cost of the MHD, and with three motors and some other electronics in it, it’s not likely to be super cheap. I’d expect it to cost at least USD $100, although perhaps it could get somewhat cheaper in volume.”
Why on earth even build a prototype if you know it will be far to expensive?
What device/appliance would you add $100 (probably noisy) device on to get a button pusher?
Sure the coffee machine in the video is probably more expensive than $100 but why not get a new one instead of it’s that important.