That doesn't explain why goods are cheaper in New Zealand[1].
If you have ever bought a pair of Levi's you would find that because they come from the same distributor the price for NZ and the price for AU are on the same tag, and the NZ price is consistently cheaper. You find the same on a lot of goods [2]
It is much more nuanced, Australia is specifically getting screwed. A combination of taking advantage of an early adopting wealthy market with heavy regulation, little local competition and our nieve willingness to play along.
[1] http://www.numbeo.com/cost-of-living/compare_countries_resul...
[2] http://www.2ue.com.au/blogs/2ue-blog/are-we-being-ripped-off... (This story mentions that Vegemite, an Australian product, is cheaper to purchase in the UK than in Australia).