Sorry you are getting hits.
I use welding oxygen it cost me $26 a month to rent a 60cf bottle from Airgas. You can pick up a non-rebreather mask i believe for $35 from Clusterbusters and you can get a regulator for under $100. I was a person that tried O2 at my doctors and it did not work at all. CHfather pushed me to try it again with the proper mask and high flow regulator and it works awesome. You have came to the right place, there are some real good people on this site that will answer any question you have. Good luck