Chuck in my 2c

I had a very cheap domain registrar in Australia (was $15 or there abouts for a couple years i think)

They ended up going under and screwing me over rather well. After a lot of trouble i ended up getting the domain again off the provider they sold all their domains too and i've had way better service with them. (boy that was painful though to start)

I think cheapest prices are down to sub $10US if you look on the web (not .au of course as they are way dearer)

So couple things to note.

Do you need a .au? if that's what you are after
Can you afford to lose that domain name if it all goes really wrong?

And i think what you are paying for is the quality of service. A good server where you can change domain details readily is critical. Automated systems work fine for me.

WEZ!

probably go with recommendations i think as a best starting point