Oh, that is interesting. I was sort of assuming that you would have to pay for each refill and that a recharger wouldn't be just <$3k.

Also, interesting links. Connecting psychometric tasks to actual monetary value is always tricky, but those studies certainly suggest there might be meaningful benefit (but the benefit will be weaker at 30% oxygen - the links seem to all be at 40%).

One big problem there is that $3k is a lot to pay up front. But on the upside, if you can change the flow rate, I suspect it wouldn't be too hard to blind the oxygen content...