If you're prepared to visit 2 stores you can get Mario Kart with Steering Wheel (or 1 of 4 other games) for $42.50. Heres what you do:
Sign up for the newsletter at EB Games here: http://www.ebgames.com.au/myAccount/signin.cfm (if you already have an account then refer a friend instead) - you'll get a 15% off voucher to be used at EB Games.
Take your 15% off voucher to EB Game and buy 2 Wii games at their 2 for $50 sale - which you'll get for $42.50. Note: Make sure you pick the right games (see below for more info). 2 for $50 sale info is here: http://www.ebgames.com.au/promotion.cfm
Take those two games into JB Hifi and trade them in for a Mario Kart with Steering Wheel - listed in their catalogue and here: http://www.jbhifi.com.au/games/nintendo/wii/trade-in/
Exclusions apply to this trade in offer and the exclusions are listed here: http://www.jbhifi.com.au/games/trade-in/excluded-games.pdf
Hehe… I just noticed that one of the games you can get from jb is Zack and Wiki which EB Games will then trade back for $48 http://www.ebgames.com.au/preOwned.cfm - lol