I order stuff from DA all the time. Order Tuesday Night, arrives Friday - UPS International Saver.
You shouldn't get hit with duties or any charges unless the invoice value exceeds AU$1,000 - if you're ordering more, like a case or something, drop Brad Lohr a line at greatboxes(at)dacardworld.com before you order, he's sure to look after you. Tell him Trevor from Australia sent you - I called in on them on my US trip last year to put faces to names. They're all pretty great guys.