ASUS RT-AC86U AC2900 Wireless Router $272 Delivered @ Amazon AU
The cheapest local stock that you can get. Over $300 elsewhere. HN have this on special for $295 ($275 after cashback, which Amazon is not in the list ) if you prefer local store.
9/12/2019 - my cashback request was approved so it looks like purchase from Amazon AU is included as well, although it's not mentioned in the cashback promotion page.