There are a bunch of places you can purchase the bits from online. Unfortunately, I suspect the shipping and handling would kill ya since your in Australia. I usually purchase mine from ENCO.
Have you tried one of your local home improvement mega-stores? My local Lowes store carries a Bosch Solid Carbide 1/4" X 1" Straight Up Spiral Double Flute 1/4" Shank. They are a bit (pun intended) pricey at $19.97 US + tax. If you need one in a hurry, though, you can't knock it. You may want to check with any local woodworking supply stores or industrial supply places.
Barring that, you can wait to hear from the unusually quiet bunch of Aussie CNCZone members. PM one of those guys or post a link in the "Australia, New Zealand Club house" section. You may get a faster response. Have you heard of, or been to, one of their GREAT AUSSIE BBQ's?