Jetstar Australia has their Birthday sale on, which includes many 'return for free' fares.
All their flights are 7kg carry-on, enough for Bali for me at least, including my laptop.
Now that doesn't work if you're flying from NZ to Aus, but….once you're there you can take advantage of it!
So here's an example. Auckland to Bali is $1024 Return.
However, let's break it down.
First: a return flight to Sydney: $422 Return
Then a return flight from Sydney to Bali: $377 Return
Total: $799 Return!