I live in Australia but haven't bought from an Australian store before, the only 1 I can think of is The Trade Binder & Collectibles - http://www.ttbac.com/
You might have already tried them though.
I can however recommend other overseas websites like the above mentioned TCG player that I have purchased from and had no problems with.
Troll & Toad - https://www.trollandtoad.com/
If they don't have a card in stock that you want there is a request item button, they usually get the stock in pretty quicly as well though the number could be random though.
You don't have to pay multiple shipping bills either if purchasing cards from the different vendors they have for each card you are after.
Trading Card Mint - https://www.tradingcardmint.com/
I find them to be really cheap but they don't stock up much when you request something, if they are out of something don't hold your breath that they will get any more in a hurry.
Tier Zero Games - https://www.tierzerogames.com/
English based store that mostly stocks up on cards from the last few years, kinda hard to get older stuff from them but they offer free worldwide shipping for orders over $50.