I use a Standard welding Oxygen bottle which can be exchanged anywhere in the US for less than $10 and a nose cannula in a  O-360.  Don’t necessarily try this yourself.   I’ve taken AF high altitude training twice at Wright Patterson and know well my personal limits.  At 22,000, for just under 1 hour over the Rockies heading east with a 80 knot tailwind wearing a pulse oxcimeter on my finger I was above the nasty turbulence and bad WX singing my semi-hypoxic rendition of Stormy Weather and getting a suntan in smooth air.  O2 stats never dropped below 90%.  I saw fuel economy rates as high as 47 MPG!

Lancairs are amazing airplanes….