Food, among other things, in Australia is fairly expensive. One easy source of nosh that is available in most parts of Australia is Cheap Sushi! This is not really the sushi you are thinking of. I will certainly agree that the idea of fast food raw fish is a little disconcerting.
For about 3 dollars- at little shops all over the place (especially near supermarkets) you can get a “hand roll” these are generally made up of cooked or smoked material such as teriyaki chicken, tuna salad, smoked salmon, and various veggie creations. They are filling, nutritious, and most importantly in OZ- cheap! The rolls are not cut into bite size pieces- basically you get a whole sushi roll and a little bit of soy sauce and eat it like you would a sandwich wrap. Many of the places have a lunch deal along the lines of 2 rolls and a miso soup for $5.50.
I carry a small container of Tamari sauce with me which is gluten free.
mmmm mmmmm good!
Other Oz survival guides to Food:
Food Survival Guide #1- Kethcup
Oz Survival Guide #2- Pizza