There isn't really a truly unlimited mobile data plan available in Australia right now, though there are plenty that let you do away with excess data charges. These are the providers offering 'endless' or unlimited data in some way, shape, or form. 

Look, the average Australian uses around 15GB of data per month. You probably don't need unlimited data. BUT if you want an extra buffer, there are plenty of plans offering crazy big data for an affordable price.

These plans have at least 50GB per month.