Long running deal.
Previous deals only for Amazon, JB HIFi and EB Games.
https://www.ozbargain.com.au/node/574828
https://www.ozbargain.com.au/node/573067
This deal is not listed on the wiki yet:
https://www.ozbargain.com.au/wiki/discounted_egift_cards
Macquarie Marketplace doesn't require you to pay membership fees to open an account and purchase the gift cards.
Shopback offers Kmart GC too but doesn't provide instant discounts, and their cashback rate is only 2%.
Suncorp is 5% no deal