There is a $150 off offer for the Nighthawk M5 when you buy it outright or with a month-to-month upfront data plan.
The offer details say
Get $150 Off When you add to an Upfront Data plan. Offer ends 30 August.
But as scrimshaw has demonstrated below, looks like you can continue without adding a dataplan.
The modem is unlocked and supports all Australian 4G and 5G bands.
I am currently using this as my main home broadband modem. Had it for a little over 4 months. Pretty happy with the performance.
I get anywhere between 300~500Mbps over 5G NR from my closest tower which is over 1.2km away with minimum obstructions (e.g: trees but not line of sight).
I believe you can skip the data plan. Pick Outright — don't click "Select Plan", just scroll down and click Next and you should be able to purchase without any plans selected