There seem to be quite a few registrars running ATM with very cheap deals, when compared to the actual AusRegistry price. (Josh displays some pricing cross-registrar at whatsinaname.com.au - check the bottom lines for the wholesale costs. Don't know how up to date it is generally)
I have assumed this is people attempting to build up clientele following the deregulation of the market (well, not quite 'dereg' but I haven't a term for 'now we can sell the damn things! hurray!'

), in the expectation that we will now be buying more domains, they can make up for the lower markup on the volume and then we will be too lazy to change registrars later when prices go back up.
*I'm* hoping that this tactic will continue, so that enough suppliers are doing it that competition keeps the price down (you hear that guys? Watch your competition! if they keep their prices down when you go back to normal markup I will jump *so* fast!).
There is no reason for Australian registrars to make more than the minimal amount that OS registrars do, ignoring the oh so slightly smaller market we have here!
FTR - Hostess is cheaper than that for raw registration.
Irritating that netregistry (hostess owner) is cheapest (I believe), as I haven't done good business with them, but - whatever, its just the registrar.