According to the folks at Kotaku, employees at some of the bigger retail stores in Australia are saying that Aussies are going to be stuck with a fat bill if they're interested in getting the full Rock Band experience. The US bundle, which includes a mic, guitar, drums, and the game is going to run state-siders $160. But down under, they're going to get reemed as the game is not bundled to anything and the peripherals are mostly sold separately. So, let's do some math, shall we?
Australian prices converted to US dollars.
The Game = $114
One Guitar = $105
Drums = $152
Microphone = $TBA
"Hardware Kit" (Drums, Mic, and One Guitar) = $275
So, the cheapest way to go is the Hardware Kit and the game which will run Aussies $389, but that's not even the full experience if you want two guitars.
Click the link for the full Kotaku story.
kotaku.com: We Hope This Australian Rock Band Pricing Isn't Real (Yet Fear It Is)