Mountain high in the US sell really good EDS "electronic delivery systems", a small elec box attached to a bottle of your choice [one of mine is quite small made from kevlar wrapped around aluminium] and used with nasal cannular.
Works great and no problem on airlines as long as bottle emptied.[so OK on the way home from ferry] can be filled anywhere that does aviation oxy.
Used often by gliders and mountain climbers. The disposables are expensive in the medium to long term.
I just bought one for my wife for less than half what mine cost in 2000 due $US!!
