if you dont need to spend a lot of times in study, the part time work should be able to support your standard living in oz, of cuz you cant expect to have private room by yourself in the city and go out for dinner often.
but if you feel great pressures from your study (like my friend who needs spend most of her after school time for assignments), you better get financial support before you come.
last, try to find a proper job with company who will register for tax, black labour gets pay much less.