Bringing in a dog from overseas is a 6 month and very expensive exercise. I very much doubt that AQIS is going to let me bring in a known noxious pest.
Edit. In most of Australia it is illegal to keep a pet fox, but in NSW you can if they are desexed and not released back into the wild [1]. I still doubt AQIS will let me bring one in.
On the other hand, cats are allowed to travel freely throughout Australia, including to and from Tasmania, and yet we can't keep our native animals as pets. I'm super keen for a domesticated Possum breed, or a domesticated Tasmanian Devil breed.
A friend got a special permit and re-habbed injured native animals in his home. At any one time he often had baby kangaroos, wallabys, koalas, etc. They're all extremely cute. Bottle feeding a kangaroo in a hanging sock is fun.
When they're old enough he releases them back into the wild.
Edit. In most of Australia it is illegal to keep a pet fox, but in NSW you can if they are desexed and not released back into the wild [1]. I still doubt AQIS will let me bring one in.
1. http://sydneyfoxtails.tumblr.com