I don't know if you are looking for clothes, but pumpkin patch has a website you can order from. I would say their stuff is similar fashion to the gap.
www.pumpkinpatch.com.au
There is also Kmart, but from what I understand you can only order what ever is in the catalogue. I don't know if that will be helpful.
www.kmart.com.au
I find that Aussies are really not into internet shopping. Which is really a bit annoying but good for my wallet. Many things on amazon will ship to Australia though. Hope that helps.