This deal is not advertised. Only available via live chat or phone, but Optus will sell you the Nexus 6P (32gb) outright on a sim-only plan for $744 + ($30 sim).
You need to cancel the plan after the first month to prevent any subsequent charges. You are not locked into any contracts.
RRP from Google playstore is $899.
Update #1: After you've recieved your order you can confirm it's been accepted here: https://www.optus.com.au/shop/welcome?defaultTab=1
Update #2: You can track your order after Optus confirm it's been sent to warehouse 'Your order has been sent to our warehouse for packaging' on startrack with optus order number: http://sttrackandtrace.startrack.com.au/
Update #3: Some users are reporting they are calling optus in advanced, and cancelling the sim service. Saving $30 :)