If you are immediately running low on iTunes credit, Coles Express currently have a deal running that will give you 15% off any iTunes card(s) that you buy.
This offer ends 17th August, or while stocks last.
A big thanks to Geoff for sending this in.
Source [Coles Express]
Other known gift card deals:
[25%] Target – Buy 2 x $20 iTunes cards for $30 – ends 3/8