I can't help on Australian-specific sources, being a US resident; however, you can certainly find most things on the Internet. You'll pay more for shipping if you need to order from overseas, but film is relatively lightweight, so you need to be most concerned about the shipping costs of heavier items (enlargers, bulk photochemicals, etc.). Exchange rates will also be an issue when ordering from overseas, of course. You could watch exchange rates and make big purchases when they're favorable to you. A few specific suggestions:
- Freestyle Photo in California, USA has a very wide selection of B&W films and photochemicals. They ship internationally, although the shipping cost is likely to be high. This might still be worthwhile if you buy a lot of film or if you go in with a group for a big order. I order from Freestyle semi-regularly and they're quite reputable, although of course I can't comment on international issues from personal experience.
- Japan Exposures sells many products that are ordinarily available only in Japan, including some Fuji products that aren't readily available elsewhere, such as Fuji B&W paper. I've never ordered from them since these products don't seem interesting enough to justify the hefty shipping costs, but you might check on the details yourself.
- eBay sellers sometimes have good deals, even with shipping factored in. You'll sometimes find Chinese-made film from Chinese sellers for good prices, for instance. This film is reportedly not as good as Kodak, Ilford, or Fuji film, but it is inexpensive, and depending on your needs, it might be fine. (I've never used any, but on impulse I recently ordered a ten-pack of Shanghai GP3 film. It hasn't arrived yet.) You can buy cameras from all around the world, of course. I've got a number of quirky Soviet cameras shipped from former Soviet countries to the USA.
Hope this helps!