iTunes has several good deals on 4K films at the moment. 4K iTunes films can currently be played at native 4K with HDR support through an Apple TV 4K, or at higher than HD resolution (varies depending on the screen resolution of the device) with HDR support on the iPad Pro or iPhone X. Any other Apple devices or playback through a PC will currently download in HD resolution. 4K support for other devices is likely to be added throughout 2018.
Combine with this deal for 15% off iTunes Cards: https://www.ozbargain.com.au/node/367181 and with Cash Rewards for further discounts.
The discounted films include:
The Prestige: $4.99, was $19.99 https://itunes.apple.com/au/movie/the-prestige/id402991820
Interstellar: $4.99, was $19.99 https://itunes.apple.com/au/movie/interstellar-2014/id965491...
Me Before You: $4.99, was $19.99 https://itunes.apple.com/au/movie/me-before-you/id1119695330
We Are Blood: $6.99 was $11.99 https://itunes.apple.com/au/movie/we-are-blood/id1018386479
Predator: $7.99 was $10.99 https://itunes.apple.com/au/movie/predator/id363331575
King Kong: $9.99 was $11.99 https://itunes.apple.com/au/movie/king-kong-2005/id291584963
Snoopy and Charlie Brown - The Peanuts Movie: $9.99 was $12.99 https://itunes.apple.com/au/movie/snoopy-and-charlie-brown-t...
Fantastic Beasts and Where to Find Them: $9.99 was $24.99 https://itunes.apple.com/au/movie/fantastic-beasts-and-where...
The Martian: $9.99 was $12.99 https://itunes.apple.com/au/movie/the-martian/id1039587313
21 Jump Street: $9.99 was $19.99 https://itunes.apple.com/au/movie/21-jump-street/id543013305
Fury: $9.99 was $19.99 https://itunes.apple.com/au/movie/fury/id922628991
Philadelphia: $9.99 was $16.99 https://itunes.apple.com/au/movie/philadelphia/id263587115
Other cheap 4K films that are still decent prices but have been cheaper in the past:
Apollo 13: $9.99
Independence Day: $10.99
Mrs. Doubtfire: $10.99
Edward Scissorhands: $10.99
Home Alone: $10.99
Tomb Raider: $10.99
Star Trek The Wrath of Khan: $10.99
Original Bourne Trilogy films: $11.99 each
Battle of the Sexes: $12.99
Life of Pi: $12.99
The Revenant: $12.99
X-Men Apocalypse, Days of Future Past and X2: $12.99 each