I saw some good discount rates on EB Games and Harvey Norman gift cards via Sun Super. They are the highest rates I have seen for these stores. 'Might be good to pay for items that rarely get discounted…think iPhones, XBox One series X, PS 5 (when they are in stock). Or stack with whatever sales they have coming up after XMas.
Promo code = EGIFTCARDS (thanks PR0r for bringing it up).
HN has 2 gift card values: $100 or $500 (you can buy multiples).
EB allows you to enter any value up to $500 (you can buy multiples).
Delivery fee is $1 per gift card.
Payment is by EFT (I tested, thanks eyebrows7 for pointing out).