You nor Oats (nor Havok if I he ends up trying to come) would need to worry about housing.
Food is a tad bit more expensive in Australia on average imo. But it wont exactly be busting you. Depending on how long you stay you could budget pretty cheaply. $50-100 a week (MAX) for stuff like food/common transport, and depending on what you want to see and do (hug koalas, box with kangaroos, hunt crocodiles, etc) then those things would be a tad more costly.
Id assume youd come to Sydney first off (thats where all of the aussies you met reside from mostly), and the big tournament is in melbourne. You should be able to get return flights from anywhere from $60-100 total.
Btw most prices im quoting is in Australian dollars, aussie currency is doing pretty well atm, but its still like 90 american cents = $1 aus dollar.