You didn't, but Ole's recipe lists it. My recommendation for a fixer would be start with Ole's quantities for Sodium Thiosulfate, Ammonium Chloride and Sodium Sulfite, then add Sodium Metabisulfite until you reach pH 6.5. Note that this is not the best fixer you can possibly mix for C41, but it may be one of the best fixers you can make easily without Ammonium Thiosulfate (yes, $200 for 500g is ridiculous). If you think there may be Silver Halide left after the fixing step, you could do two bath fixing for good measure.
PS: Have you tried contacting Fototechnik Suvatlar? They stock the whole range of photo chemistry and may ship to Australia.