In the new July 09 issue of PC Authority magazine we have a 10-page guide to Broadband Internet deals, including plans comparisons, and tips and tricks to getting the best possible deal for your money, including the following details about "reserve tanks".
Plans that shape you when you hit your quota are a much better option for home users.
A few plans of provide the best of both worlds. Netspace and Westnet, for example, give you the choice to accept shaping or to pay for excess if you really need top speed to operate. Some other ISP's allow you to purchase extra chunks of quota to top you up for the month.
Exetel has a useful option as well: instead of excess charges you can choose to get an extra 2GB of data for general browsing use until the end of the month, but if you exceed even that then your normal excess charges double (not mentioned on the Web site anywhere we can see, but confirmed to us by Exetel's sales department). Gotalk has something similar - a "data reserve" of quota that can be activated when the user hits shaping speeds.
Also in this series:
How to Get a Good Broadband Deal, Part 1: Naked, bundled, pre-paid
You can read more about wireless plans in our Broadband Buyer's Guide: Fixed vs Mobile
If you're interested in our speed tests of each Australian wireless broadband provider, see our Mobile Broadband Group Test