I like to use Horze.com. They're a european company that ships to 43 different companies, and they just started selling in the United States.
They have a site especially for Australian orders, here is is: Home | Horze Wholesale
Although some people above are saying that "cheap" and "quality" don't go together, they actually have very fine quality products for often a much lower price than other online stores or tack shops. I talked to a brand ambassador at a horse show once, and they told me that it is because they manufacture ALL of their own products directly, and therefore other companies aren't making their "cuts" and raising the prices.