Need cheap data for home internet

Just moved into our new house where we don't have our landline connected yet. Telstra have indicated it might take a few weeks to get connection.

So looking for some temporary way of getting cheap internet data. Both our mobiles have 1.5gb data each, but we are always afraid that we might run over our data limits.

Can anyone suggest cheapest way of getting around 2gb data that we can put in our spare mobile etc and tether to our laptop and mobiles while at home. Or ant cheap data card being available?

Thanks