Effectively, yes.
We're in a country where we pay $50/month for 150GB quota on ADSL2+ which connects at 5Mbps.
There's a $10/50GB overage charge. So if we were to hit the quota you have, we'd be paying roughly the same ($70/month). Note that the price listed does not include taxes and fees, which bump it up to within a few dollars of your $79 price point.
http://www.iinet.net.au/internet/broadband/adsl/