Mate. That sounds great. I called in a couple of months ago on my lunch break (DSTO) and had a chat to one of the guys there about CO2 and their "Supa Mix" blend. The deal at the time was pretty much same as BOC and AirLiquide - you have to rent the cylinder for $$ + pay $ for refills.
Be sure to post your findings.
Be sure to post your findings.