While I am unclear as to when they started, Optus has begun advertising the Apple Watch Series 4 on their online store. Allowing you to purchase one on a 24-month plan with monthly-included data and more.
According to their website, the aluminium watch in both 40-mm and 44-mm are available on two plans. With the option to have 3GB or 10GB of included data each month along with some extras. Including the ability to add data-free entertainment (music, mobile tv, national geographic, and Optus Sport).
Both plans also come with Number Share for A$0 a month with an eligible Postpaid Mobile Plan. Number Share allows you to make, receive calls and use data on your Apple Watch. Because you require a mobile plan or SIM-Only plan, it means when you add an Apple Watch plan the data-included can also be shared accross both plans.
Plans and Pricing
At the time of writing, Optus is offering the 40-mm Apple Watch Series 4 at a starting price of A$35/month over 24-months. Or A$40/month for the larger 44-mm watch.
40-mm: A$35/month with 3GB or A$40/month with 10GB
44-mm: A$40/month with 3GB or A$45/month with 10GB
In terms of colours, you have the option of selecting Space Grey, Silver, or Gold in an aluminium finish. You can learn more or order one at Optus.