Jon Saxton's Website is a great resource for Australian predecimal coins with a particular emphasis on bronze coinage die types.
Stuart Andersen Pty Ltd lists a good range of Australian coins including PCGS slabbed coins and a selection of varieties and errors.
Drake Sterling lists high quality PCGS slabbed Australian coins.
The Purple Penny now have a retail shop in Adelaide.
Sterling & Currency are located in Fremantle. As with the others I have mentioned, Andrew has the highest integrity. Additionally, the articles on his website are well researched and definitely worth a read.