Just saw in reply to this post - http://www.ozbargain.com.au/node/96075 - there is a cheaper deal available with goget if you are a student.
There are no monthly fees and no sign up fees. This is only a student offer, beneficial for me, hopefully for others too.
You can book a car for $5.65 an hour (plus $0.40/km) or $68 a day, with 150kms free. Basically equates to the "go frequent" plan but without any of the signup fees or monthly costs. Note there is a $500 preauthorisation.