Similar to https://www.ozbargain.com.au/node/409264 the $20 off Optus $80 tablet plan is available for iPads (including Pros which will be replaced soon) too.
If you have a mobile with Optus, you can get another $10 off per month.
Available for new and recontracting customers.
(Note also that the deal may not show up on some browsers. Try a different browser or clear cookies if so.)
Offer extended to 18/11/18
Update 2: Offer extended to 03/02/19