iiNet currently have an offer, where if you sign up to one of their Internet broadband plans you receive a bonus 80GB data on their $15 p/m for 6-month offer plan. (Plan has no lock in contract)
Equates to 120GB for $15 a month. (Note: after 6 months the plan reverts to: $29.99 p/m for 120GB).
Includes unlimited talk and text within Australia, and uses the Vodafone network.