Costs can vary quite a bit depending on if one is local or visiting from over seas. What I mean by this is whether one has their own vehicle or have to hire. That aside, my rough estimate (for my self and my wife) is AU$250 per day. This includes fuel, food and camping/lodging. Mostly camping. Food we buy in bulk to take along. Keep in mind Australia is a continent on its own, so depending on where you want to travel to many miles need to be covered to get from one point to another. E-mail me on duncan@overlandjournals.com if you need any specific information.