Talking about cpap machine, I did some research on it, and found that they are regulated medical device and cannot be purchased without prescription.

I suffer chronicle dry nose, moderate empty nose syndrome on the right side (due to surgery done 20 years ago in China), and Deviated Septum (due to injury as kid). One thing often happen to me is during middle of nigh sleep, my left nose duct will be extremely dry, causing me to wake up and switch side (it seems my nasal cycle is completely gone).

One idea I wanted to try to fix is to use a cpap + humidifier to pump moisturized air.

And I found that I have to get prescription, which I tried with one lab sleep study causing $3000+, and concluded that I do not have sleep apnea, which is one of the symptoms to qualify cpap prescription.

Then I started to look for off market cpap machine on Craigslist. No luck, the machines are often old, and beat up after long usages.

I did not seriously research if cpap has risks to normal people. But it does not seem harmful, unfortunately it has to be regulated and possibly also become very expensive.

Edit: Thanks for the good recommendations. Buying from Chinese site (I often forgot this), nebulizer, etc.