expired TM-AC1900 (Rebranded RT-AC68U) Wireless-AC1900 Dual-Band Gigabit Router by ASUS - US $93.57 (~ AU $117.50) Shipped from Amazon
A good price for a great router, might be interesting for those who don't care about the local warranty and are able/willing to re-flash it into the original ASUS RT-AC68U product (here's how). I personally use it with a well-respected Merlin firmware.
Might not be technically a deal, but IMO it is, considering the lowest available prices for the original RT-AC68U router.
UPDATED, to make it clear, this is just a router, it does not have a modem. I have not tried it with the original T-Mobile firmware as I re-flashed it right away. I myself use it on an NBN FTTN connection together with a dedicated VDSL2 modem in bridged mode, particualrly this Zhone 6712-W1, also from Amazon. When I first got connected to NBN (via TPG), I tried a few different modems and Zhone had worked the best. Since then, I've switched away from TPG to a small telco, but this modem still works reliably. Your mileage may vary, but you certainly can buy these two things together and save on combined shipping. Especially, if you like tinkering with networking hardware :)