This is supposedly an AMEX deal but if you sign up using the above link and buy something of equal or less than $10, you won't have to enter any credit card details. I couldn't put that link to the URL/Link section for some reason.
You will need to sign up with a new account.
The voucher will be available at checkout.
The only things I could find with free shipping are from the superhero merchandise sale: http://www.ozsale.com.au/ItemsList.aspx?cid=10&saleID=6TPq-S...
I bought the Dark knight Mug.
Hope someone finds this useful!
Details from amexconnect: https://www.amexconnect.com.au/Offers/689/Join-OZSALE-and-re...
Mod: Fixed link
Note: "Shipping will take up to 21 days after the end of the sale."
So match expectations accordingly - it may take a while.
EDIT: Looks like the deal has expired after 8000 clicks! Hope Ozsale.com.au follows through with the orders.