Tatonka Barrel Bag Backpack at Bagworld, only $84.95 + free shipping
The Tatonka Barrel bag backpack is a 53cm travel bag (45L capacity, 1.3kg, 50 year warranty) of approved cabin size proportions by Qantas. It's on discount from Bagworld for $84.95 plus shipping is free.
Wild Earth has the same bag for $101.54 while Bags To Go has it for $103.95 (including shipping).
It's available in 4 colours: black, blue, red and lemon.