I saw Barrel Escape at ToysRUs earler in the week, so I assume they have the exclusive.
While at Myer today I got a World Racers 8899 Gator Swamps set for $25.70, which is somewere around 66% off (They had two of them but no other World Racers sets).
They were in the clearance section but not labbled.
So worth keeping an eye out if your loca Myer has any of the World Racers as they may be discounted.