I have refilled O2 in Darwin from many maint facs, most recently from the Cessna dealer who has the shiny DC3 parked out front (can't remember the name of the fac, SAE perhaps?
As the Dr says, price ranges from a carton of beer to about $90.
I used to refill extensively and I cant recall ever removing the bottle from the plane. Carried our own adapter in the plane.
Hawkers used to do ours when in TV, but i dont think that they are there any more and so, the maint place opposite blue water did ours a few times - can't remember the name... the engineer who looks like David Hughes from ch10.
