In-store only, probably the last chance to stock up on discounted eShop credit for a bit.
Bonus discount for those who got the Amex JB Hifi cashback offer, get JB to pricematch this discount and pay with Amex to stack discounts.
You'll need to get $120 worth of eShop cards to maximise your discount at JB.
$120 * 0.9 = $108
$108 - $20 = $88
[(120 - 88)/$120]*100% = 26.7% discount