Another thing to consider - should the smoke lie low or be allowed to rise? To stay low will need a different kind of fogger, usually with a chiller e.g. a glaciator or something similar, possibly using CO2. These are best hired as needed, as they're even more expensive than the options already under consideration. I've seen some good low foggers from Look Solutions, too.
Other names to throw in the mix for research might be Swefog and Smoke Factory, but of course I have no idea if these are easily available in Aus.