LAKA, i have bought 2 of the drop checkers from ebay (broke the first), so yes you can get them in Australia (cost about $36.00 delivered). I also have 5lt of Tom's original 40°KH solution (4.99gr bicarb soda to 5lt of distilled water). Let me know if you want some of this. I can even dilute this down to 1lt of 4°KH solution if you can't do this yourself.

P.S. I have been using the drop checker method for about 6 weeks and its a very big improvement over any of the other methods to determine CO2.