I have one of those machines (for my snoring/apnea issue) and I can tell you that they are not cheap. You could probably sell it in its current condition for $200-$300 if you sold it "for parts" or a similar description. It's relatively easy to clean up. Just spray it down with some Windex and wipe it off really good. There are people who use this equipment and they know how to reprogram it and sanitize it for their personal use so I doubt that you would have a problem with finding a buyer for it.

But being that it's a medical device that's only available with a prescription, you might encounter some issues with posting a listing.