As pointed out in https://www.ozbargain.com.au/node/128771 you can get 10% off with the gift cards and a further 10% with the Christmas cracker, however it isn't just limited to XBOX LIVE Gold 12 Months.
You can only buy gift cards up to $100 but you can get multiple.
Purchase Gift card first (10% off).
Link to Gift voucher http://www.ozgameshop.com/gift-vouchers.
Redeem it for store credit at http://www.ozgameshop.com/redeem-gift-voucher, then purchase your items with the above code.
It will bring the price another 10% totaling 19% overall.
For example i bought
xbox live 12 month code (email) 49.99
Battlefield 4 limited edition (xbox one) 74.99
totaling 124.99
then i bought gift cards totaling 112.48 (10% off using code)
one for $100 which with 10% off was $90
one for $12.48 which with 10% off was $11.23
Totaling $101.23
Making battlefield 4 for xbox one $60.74 and 12 months gold 40.49
other games prices using the above are as follows for PS4 and the same or similar for xbox one:
Battlefield 4 Limited Edition Game
$60.74
FIFA 14 Game
$60.74
Assassins Creed IV 4 Black Flag Game
$60.74
Lego Marvel Super Heroes Game
$48.59
Call Of Duty Ghosts Game
$52.64
NBA 2K14 Game
$59.12
Injustice Gods Among Us Ultimate Edition (GOTY)
$44.54
Killzone Shadow Fall Game
$52.64
Battlefield 4 Game
$59.12
Assassins Creed IV 4 Black Flag Game
$51.02
Need for Speed Rivals Game
$59.93
Xbox One Controller
$56.69
Didn't read the description, sorry