The traffic limits tend to be so low its not funny, mainly. Most of them are < 5G a month and nowhere near the 3 billion G you get for $5 overseas. And its rare to see an Australian host for less than $20 a month, although I'm sure they exist.
Its been a while since I looked but last time I checked I couldn't afford anything Australian.
Edit: Ok, since its been so long since I looked, a google search turned up about 20 hosts that cost $36-55 a month and one that cost $8, which stood out like a sore thumb. And a few at $3 with huge amounts of transfer that are clearly just reselling overseas hosting.
We pay about $20 a month at the moment and are very, VERY happy with our US host.