Australians have always been ripped off with film prices. The internet allowed price transparency so now I'd guess most regular film shooters buy from overseas, where savings can typically be 30-50%, including postage.
I'm grateful to earlier posters for giving me some pointers to other films that may meet my needs if prices continue to rise.
Here's a comparison of Freestyle vs Vanbar Imaging, a large photo warehouse in Sydney. Vanbar prices are typically a few dollars cheaper than most retail shops (although it's very hard to find any retail camera stores that stock bw film or Portra).
Tri-X 400
Freestyle (USD) prices:
135-36 - $4.39 (currently discounted 20%)
100' - $89.99
Vanbar Australia (converted to USD) prices:
135-36 - $8.49
100' - $144.85
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HP5+
Freestyle (USD) prices:
135-36 - $5.59
100' - $64.99
Vanbar Australia HP5+ prices
135-36 - $13.29 a roll, but currently discounted to $20.45 for 3 rolls
100' roll - $92
Edit: moral of the story: if you're visiting Australia, stock up on film before you leave!