I would look into whether the specific type of machine he is using is what's not covered; it could be that the insurance company covers other CPap machines and their supplies.
If it is truly as you say and your insurance company covers absolutely NOTHING to do with CPAP machines and supplies, I would ask your doctor to write you a repeal (or whatever they're called), stating that your husband needs this machine because of health risks (ie, stroke or death). That might not get them to cover it fully, but maybe they will at a percentage. I'd make sure that the cost of the supplies is included with the doctor letter, not just the machine (my husband uses one; we're covered by insurance. The different pieces--mask, hoses, etc.--need to be changed/bought new every so often). This is the one I would be gung-ho at the moment about, because for your husband, the machine is a MEDICAL NECESSITY. I have a suspicion that a medical insurance company needs to cover--or offer to cover at a percentage--something that's needed as a medical necessity, though I could be wrong. (It would be like being newly diagnosed as a Diabetic person and your insurance company stating that's not covered. Excuse me? Come again? Really? When I can die if I don't get my insulin? It's the same concept.)
If having your doctor intervene and write letters of medical support doesn't work, I would begin searching for on-line sources where you can purchase the supplies. You're going to have to pay out of your own pocket for this, of course. (Also, your husband is going to need periodic check ups to make sure the machine and accessories are working correctly, that the pressure and humidifier (if he has one) is functioning properly--your insurance company covers all the doctor visits, doesn't it?)
IF you have to go this route, get a letter from your doctor stating the medical need for this machine/supplies, the severity of the problem your husband has, that he needs to use a CPAP machine as well as periodically needs to replace/change the mask/tubes/etc. KEEP that letter with your taxes along with all of your medical receipts. I know there is a limit or a certain amount of money you have to spend before you can deduct your medical on your taxes, but I would definitely keep all of these receipts and see if you're able to do so at tax time. We use alternative medicine, and I give my CPA all of my medical deductions, just in case we qualify that year to take them. So far, I've been able to deduct something for spending my own money on medial treatments for the past three years.
I understand where you're coming from; the machine and the supplies is expensive if you don't have insurance, or even insurance covering a portion of the costs. Good luck.