Fwiiw... when I needed cpap ~ ten years ago, I was aghast at the cost. Turns out there is a community at cpap dot com that links to a used market. For a couple of hundred I could get the machine I needed (which costs less than insurance copay on a rental for one month)
The community was very supportive, at the time I used it, one person sent me his full face mask to experiment with.
Like many I had trouble to begin to use the cpap machine. For me the key was to track my numbers using software , normally used only by cpap techs, that was available on the board.
They also told me the secret button push needed to reprogram the used machine to the pressures I needed.
Cpap, IMO, is a direct medical device insurance racket. You have to struggle to get the tools you need at an affordable price
Secret buttons, proprietary software, sheesh... they have got to be kidding.. but they are not.. it's just a technique to link the unsuspecting to the preferred vendor, just to squeeze another buck from the sick