It's slightly cheaper to buy from the epic game store with their $15 coupon offer https://www.ozbargain.com.au/node/672147
However, if you were unfortunate to buy the GTA Definitive edition trilogy you can use your $10 coupon (Appears to be $15 Aud) to get this down to $15.95
Is the GTA Definitive edition trilogy really that bad haha