If you have an Australian Vodafone branded handset you will be able to use it. Otherwise, they won't be able to give you the unlock code for it.
I think i have posted enough to actually post a link now LOL. I think this is the link (it is blocked at work and I can't get directly to it.)
Answer <- This link.
Otherwise, if you go to
Help & Support and follow the Unlocking link from there, you can get to it.
I am not sure of the price, I unlocked a different phone and i "think" is was $75. can't remember off the top of my head.