I was at the Myer Sydney store earlier this afternoon and they had at least 5 of each of the PotP Legends, Deluxe and Voyager classes in stock at RRP (didn't remember seeing any leader classes).

They have a 20% off toys sale until the end of this week if you buy 2 or more toys. I bought Slug, Swoop and Grimlock for my son's upcoming birthday and the total was $95.88 (RRP $119.85). I don't believe any of the PotP line are available through their online store.