Most of the jobs for economists are in Canberra. I think government departments have cadetships where they pay for your uni as a school leaver, two places would be the Australian Taxation Office and the Department of Finance and Administration. There is Treasury again that's in Canberra.
There are other jobs out there in a whole number of areas from working as a trader or jobs in all the banks.
What I will say about those jobs is that they hire people with who have worked in the industry a while. The only way you get to see what its like to work in Economics and can figure out what Economists do is by working for a government department first. That's were you get your experiance. I guess the major motivation for this kind of thought is that as an economist you are essentially analysing policy most of the time; what better way to understand how policy decisions are made then by working where they are made, and then hiring someone from one of those departments. E.g. a number of economists working at big banks or in the private sector, if not all, perviously worked in the public sector (i.e. government jobs) - a lot of forecasters worked at Treasury; Treasury generally seems to be where it's at in terms of Australia. RBA is up there I can't say which one is better, I think maybe treasury as they look at more; it changes depending on the circumstances. So then I think your first focus should be on getting a public sector job. To do that you need honours in economics or econometrics. From there you would want to land one of those government jobs as a grad, and then be there fore two years getting experiance. Then from there your options in terms of finding work are much wider. Then you will be able to get jobs at Banks and other areas.
Hope that helps.