Well after Booking.com's price gouging for cashback partners was laid out by many OzBargainers, I've noticed ShopBack are doing 16% cashback on Expedia Australia.
I've checked the property I've had my eyes on and it's actually cheaper than Booking.com (and everywhere else), and the same price when clicking through from ShopBack. YMMV and if you find Expedia are also price gouging for cashback sites please neg away!
Shop back is terrible for hotels. I had to submit proof of booking to claim my cash back even though it tracked. Still waiting for approval despite my hotel dates are over 150 days old. Pathetic!!