I got a notification from Booktopia advising if I used the code POTTER50 that I would get 50% off the rrp ($120) of the Harry Potter paperback box set if I ordered before Sunday at midnight.
It knocked the price down to $60 but Couldn't use any other codes though.
Not sure if its targeted just if you are signed up for their notifications, or if it will work with cashback (I tried to be safe) but hopefully it does!
So its a $30 discount on current selling price of $90