I've been buying my supplements from iherb usually but decided to give vitacost a go since they've started shipping to Australia.
Was surprised that most of the products were cheaper than iherb, and with their current 50% off second item on some of their own brands it worked out I saved around $25 USD on my order.
For anyone who's wanting to lower their cholesterol I'd recommend getting the Vitacost Phytosterol Complex with Beta-sitosterol — 240 Tablets which is a bargain compared to buying the special margarine. Last health check the doctor was amazed at how high my good cholesterol was - unfortunately it's not getting the half off second deal.
DHL shipping was a reasonable $10.99, once again slightly cheaper than iherb.
Vitacost have great pricing for pretty much every product.
However, a friend of mine placed an order last month and he received the goods over 25 days later. He definitely wasn't happy. I have also heard other negative customer service feedback about Vitacost but if you can handle slow shipping, go for it!