Here we go again!
Amaysim at Shopback shows the 80GB sim plan with $35 cash back and its $20 to buy at Amaysim so that should be a $15 profit.
The plan reverts to 80B/ $50 ongoing so all the value is in that first month.
Amaysim runs a 28 day 'month' and uses the Optus 4G network.
EDIT: Tracking came in but shows $14 ($35 on Shopback)
PM-ed the rep and asked him to sort this so please beware the advertised amount seems different than the tracked amount