Camping in a caravan park! Borrow gear from family or friends and DONT go in school holidays - it can be really cheap ie $20-$30 per night and they are often in great locations and have good cooking facilites etc. You would just need a tent, eskys, camping chairs and table and something to sleep in/on eg swag or airbed or camp stretchers etc. You'd be surprised how many people you know have these sitting unused in thier shed/garage (I know we do) and would be happy to lend them.

You can eat lots of bbqs/cook your own food so no more exxy than eating at home.