Better than half-price promo on page 33 of this week's Woolworths catalogue.
Pay $8 for the $20 pack, $12 for the $30 pack, and $15 for the $40 pack.
The catalogue doesn't specify if this is an in-store or online promo, so I'm not sure if Cashback will apply.
You also receive 10% off your shop once a month if you have your Rewards card linked for 45+ days and the service is still active.
Usually online price matches instore price on Wednesday.
Possibly free for online purchase after cashback.