I think for me moving out was one of the best things I ever did. Even better is if you can live on campus in a hall or something for the first year or two.
The cost of living is substantially less in Adelaide compared to most other capital cities and this can be budgeted for. I took a gap year, worked, saved like crazy, and now I have to survive until I am 22 on my own money before I get any centrelink. This isn't as bad as it seems because as I've taken a gap year I'm already 20, I can work over the summer holidays (and perhaps during term if I could be bothered) and the cost of living is OK. I think not having a car really helps me, I live on campus so I don't really need one and it saves me HEAPS on rego, insurance, fuel etc.
I think that many people trying to get into medicine are highly driven, A type personalities who see their goals (getting into their home state) as being the be all and end all and as a result look upon moving interstate with disdain. It's really not as bad as you think, you make friends/connections in your new home state, your friends back home will either keep in contact or they won't (and you won't care as you have other friends) and you get to study your degree of choice. I'm not saying it's easy for every one but once you're in, you adjust quickly