You can have a $2 meal. Eg would be an omelette, you can get a dozen eggs for $3.50 and if you have a few pots of herbs and onions ($1 a bag at Aldi today) and some cheese your 3 egg omelette is $2 a person, even if you add some bacon ($7 kilo)
You just need to shop the basics and cheap cuts of meat. I learnt to cook cheaply with a French cook book called "I know how to cook" by ginette mathiot. The book is about a hundred years old and for old French housewives, so uses cheap meats and veg. Instead of chicken make beef Bourgogne, the stewing meat only costs me $3/4 for four people and just a bit of cleanskin wine, potatoes and carrots. Oats I found cheapest at Harris Farm markets, $6 a kilo for organic oats. Honestly food cost isn't all that bad, you'll be earning much more here too. You can get a five kilo sack of rice for $10, delicious pink lady apples for $2 kilo. Aldi bread for $1.50 for multigrain/whole meal and I think white bread is $1. Even if you don't have Aldi the big supermarkets keep the basics at the same price. So coles bread is also $1.50, oats were about $2 a bag, pasta for $1. Don't get the .65 cent pasta, it's atrocious. Coles $1 pasta is the best. Canned tomatoes are .80 cents. Coles is actually very good for staples, their pasta, canned tomatoes, Brie ($2) etc are all very good quality.
Costco is expensive here, unless you're buying a lot of processed foods there isn't much price difference. A big saving will be commuting. If you can get next to a train line or biking to work you will save big. For a phone aldi mobile is cheap and the cheapest way to call home would be to get a free wifi hot spot and Skype. Considering how good the pay is here if you're frugal you can save much more than in the US. As a college student I worked a minimum wage job and could still afford an overseas holiday every year. So yes, Australia is expensive but the increased earnings more than pays the way!