A displayed price published in a catalogue or advertisement that is incorrect, can be corrected by publishing a retraction to a similar circulation or audience to the original advertisement.

Even their catalogue online still had the incorrect price for the whole duration of the sale period and no notice of a retraction on their website. Surely, that alone would be a breach of it's fair trading obligations?

Their customer relations office is closed now, but come tomorrow, I'll be calling them up and hinting about "fair trading" and "ACCC" in my conversation complaint with them...

Anyway, my wife spoke with a friend that works at BigW and she said whenever there was a pricing mistake in their catalogue, they had to sell it at the advertised price until a correction notice was put up on the shelf of the item and on all their checkout registers. But that is just the BigW policy on this.

I'm always mindful to be thank the staff for allowing me that grace (remembering that they don't have to do that). If they decline the sale from me, then I just say something like, "That's alright. Thanks anyway." and leave it at that - because they fully entitled to withdraw the item from sale if they want to.
It's the people that kick up a big stink that usually wins out. I'm going to try that tactic tomorrow