CPAPtalk.com

I buy my own. Sleep study paid by insurance and first data-less CPAP & mask. Rest I've paid for. I did order one of my Hybrid masks through insurance and they billed $750...yikes! I can buy it from our host for $119 (I get one every year or so). I just could not deal with that gouging.

Medicare covers 20% of all my supplies, but I still buy some supplies from our sponsor. Less hassles and I can afford to do it (yet).

Odd, Medicare pays 80% of the "negotiated" price for supplies, and my supplement pays the remaining 20%.
I was not aware of a Medicare plan that only pays 20%.
Maybe your DME is dishonest?