We've talked up the merits of practicing savings and investment strategies in a simulator before, but many online simulators aren't geared particularly to Australian conditions. Investorville, developed by the Commonwealth Bank and designed to demonstrate some of the challenges of investing in property, is an exception.
On the site, you can set yourself with one of five profiles (ranging from rookie to empty nester), which gives you a set budget to invest. Then you search for a suitable property, and the site runs you through how much you'll spend and how much you're likely to make. Working through the process can be time consuming, but it does give you a solid idea of the basic issues involved.
Investorville is free to use, requires signup.