GG375,
Might be worth trying Shooters Warehouse in the ACT for Alliant [formerly Hercules] RL-15. They keep a few US powders. Contact details are at http://www.shooters.com.au/

Failing that, the Oz Alliant distributor comes up as Wesfire in WA, http://www.q-net.net.au/~wesfire/ They have a list of retailers, though you may have to wait a while for a single can order!

For ADI powders, they list loads for AR2209, 2213, 2213SC and 2217 in their manual. Check the ADI website, if you don't have a print copy.
Cheers,
Doug