CDWow Australia is currently selling this well-acclaimed, yet poorly known game for the very low price of $26.95, including free shipping (RRP of most Nintendo Wii games is of course $99). Considering how enthusiastic reviews have been for this game, it's worth checking out.
Although there's no expiry date on this deal, there is only limited stock available.
EDIT: Now sold out, apparently.
Zack & Wiki is a really good game.