As of yesterday iHerb's shipping to Australia required a minimum of US$40 in order to get the US$4.00 flat rate shipping, however today it appears that the US$4.00 flat rate shipping will apply to any order no matter how small. Note, this is the Australia Post shipping option.
I also tested this on a few of the weightier cheaper items and the US$4.00 flat rate applies. It's up to 4.5kg (but will cut off when your order exceeds $120.00)
This reduced shipping might be helpful for those who buy heavy proteins or Quest Bars:
http://www.iherb.com/Quest-Nutrition
Or great for the girls buying Real Technique brushes (which are approximately half the price of Priceline):
http://www.iherb.com/real-techniques-by-samantha-chapman
For those first time buyers my referral code is OKE962, which will save new customers US$10 on purchase of US$40 or more, or US$5 on orders less than US$40.
thanks for the heads up - gotta stock up on some vitamins and iherb seem to have a higher strength vitamins and a lot cheaper.