Went past the local Dick Smith store, at the corner of Little Collins & Elizabeth in Melbourne, and saw that they had DJ Hero for PS3, Xbox360 and WII for only $50!
I would've bought one if I didn't already have one.
Pic taken at the store: http://i50.tinypic.com/34o2g6v.jpg
The DSE online still has a listed price of $98 so this may apply only on a store to store basis.
Cheapest ive seen it