Equivalent to 20x Everyday Rewards (EDR) points if you convert EDR to Qantas Points anyway.
Make sure you drag the slider in the "Points Plus Pay" box to 0 points, so you pay with cash only and earn the full bonus points.
But significantly easier as no need to go into the store and hope the Apple gift cards are in stock.
All denominations seem to be eligible ($25, $50, $100, $200, $250, $500).
Literally just bought with 10x Flybuys today. Not sure how which is better