we are doing the same thing ATM, we have been told by the com bank that to get a loan you need 10% deposit so if your looking at 300k then you will need 30k deposit, BUT if you have a exsiting loan or credit card with the com bank then you only need 5% deposit, so you would only need 15k... we got told the best thing to do would be get a credit card with them with a $500 limit , cut it up so that you dont use it... then after 6mths with the card you are able to apply for the loan and you only need 5% if that makes any sence...

but in three years the GFC should be over and the world should be on the up again so you might be able to get a loan with next to nothing again...

good luck with your savings