OzGameshop have Halo 4 on pre-order for $49.99.
There seem to be two different ones on the website, one for $64.99 and this one for $49.99.
Get in while it's available!
As per the website:
This is a pre-order - the item will be dispatched to you on or before the release date of 06/11/2012 - subject to change by the publisher.
Please note: this is the NTSC-J version of the game which is fully compatible with PAL systems.
Thanks ProspectiveDarkness
That's reason for the price difference - this one's from Japan / Asia. The only noticeable difference might, might be some Japanese or Chinese on the cover. I'm not sure what the state of such imports is these days (in terms of foreign lettering, that is)