Once fired brass to get shipped from US to AUS

Well it is not so easy as to just send it to you.
If you want to export brass from the US legally, you will need a export permit, witch costs a couple hundred dollars and takes a time to get approved.
So it's not just to press the buy button and wait for it to arrive, in general for small purchases like that, using the time and money to get a export permit is just not worth it.
 
managed to find 500 308W for $165 at Av ballistics in Australia should work out easier but it would still be useful to get some lake city brass
 
Reloading components, bullets brass, primers and powder is export controlled.
Shotgun shells are not.

What the exact rules and regulations are and where you find them, someone can probably answer I'm not from the US, and have never looked for them myself..

You need a personal export lisence, and depending on your country a import lisence, or a proof of not needing it.
Some companies like Brownells and SInclair does it for you on some products for a fee, only bullets in this case though.

Reloadinginternational does a lot of bullet and brass export to private persons if you have the need for it.
Or want something like JLK bullets.
You need to pay a fee for it though, and wait to get paperwork in order.