Big W is selling $100 iTunes cards for just $70 each, a 30 per cent saving. That's a decent discount, but there's quite a few caveats.
Firstly, it's an online-only deal, and it expires today (September 22), so you'll need to get in quick. Secondly, it's restricted to two per customer, though commenters on OzBargain have suggested you can get around this by placing multiple orders.
Thirdly, prior experience suggests that Big W online often sells iTunes cards which aren't actually activated when they ship, which is a nuisance if you want to use the cards as soon as they arrive. You might well be willing to put up with that hassle for the saving, but forewarned is forearmed.