depending on what you are looking for you can get lots of good stuff at either
lowcarbcentral.com.au or lowcarbzone.com.au there have been a few others at different times but doesn't seem to be anymore.

Try some health foods shops around as well, I have always found the people in the health food shops really helpful when I have asked for help with low carb foods, some have even gotten in some stuff for me when I enquired about it.

I also found some low carb (sugarfree) lollies and chocolates in my local IGA (Brisbane), but have found not every single on has them.

Also - Terry White Chemists have Tony Fergusson stuff, some of which is low carb