You don't really need a two gauge regulator though. Just weigh your bottle when full and when empty so you can then work out how much gas you have. The second gauge on the bottle side doesn't move at all until your essentially fully out of gas so a bit useless. This is only really of any importance if you happen to find a cheap 1 gauge reg, but most are two.
I have heard that the fittings on the US gas bottles are different to those used here, hence the reason no one seems to import gas bottles from the states, but I have no idea if this is true or not and if yours fits jayse and it is an american one then I suspect that they may be the same.
I tried to find out if the aussie CO2 bottles were CGA-320 fittings but got no where with it. Worst case scenario you could always get a brass adapter made up for you yank reg to convert to an aussie CO2 thread.
Throughout the world, carbon dioxide cylinder valves have a special thread. In Europe, Africa and much of Australasia, the thread conforms to British Standard 341 Part 1 (.860 in x 1/14 in W) or the direct European equivalent (DIN 477, SN 219505, etc). These threads are in effect interchangeable.
America CGA 320 and Japanese JIS B 8246 CO2 threads are different and are not compatible with each other nor with British/European CO2 threads.
Sorry all sold, and I'm not getting anymore (out of the batch of 5 that I bought off someone else, there was a dud one, and I'm wearing that cost, so no more from that source, but that's business).
If I was after a regulator I would look at the UK. Not as cheap as the US, but still better than $120-$150 that you often see in some shops, although the saving will be small and probably not worth the hassle.
You can buy a 2 gauge regulator from the UK for 30pounds and postage would be about a further 7pounds. Based on today's exchange rate 37pounds is equivalent to AUS$95. So for around about $100 you would get a brand new 2 gauge regulator, but have to wait about 6 weeks.
I've spent a lot of time looking at the issue of CO2 regulators and bottles, and tried to work out the best way around the higher expenses in Australia. My conclusion is bite the bullet and get a regulator from Australia, and use a fire exinguisher as the gas bottle (such as from Goliath's). You should have no problems getting this refilled as it's an everyday item and need. When you start faffing about with non-standard items you have to find someone who is willing to "help out", and these people can be rare. Plus let's all remember that CO2 is under pressure and the more you mess about with it, such as adaptors etc, the more elements you introduce which can go wrong, and with pressurised gas that can have tragic results. I recommend to keep it simple (particularly for desk jokeys like me).