Update on my quest for a reasonably priced supply of CO2.
I found Eversafe fire protection in Maddington really helpful
U 1/ 29 Emerald Rd Maddington 6109
(08) 9493 2044
Ask to speak to John and say what you want it for, he will sell a 3.5 or 5 kg steel CO2 extinguisher that is in test, filled with the dip tube removed for about $90. Ali cylinders are more and you would need to ask him what he has in stock at the time but for just sitting next to the fridge in the shed I am happy with steel. You will need to give him a bit of warning so don't expect him to have one prepped and ready if you just walk in the door. I was in a real hurry for CO2 so at the moment mine looks like this as the dip tube is still in it, hopefully I wont need the trolley soon!
So for less than the cost of a years rental I own a cylinder with 4 more years left in test, excellent!
Cheers
Ausdb