Amazon currently running an offer of 2 x 4K Ultra HD titles for £30.
They're really expensive as it is, so I figured this might help some out.
Buy two 4K Ultra HD titles for £30 when dispatched from and sold by Amazon. This Offer ends on Sunday, June 25, 2017.
Obviously these require you to have a 4K tv, and relevant player for to play Ultra HD movies. (in case of any doubt Xbox One S will play them, but PS4 Pro will not).
If any titles take your fancy then you might also want to cross check them against http://realorfake4k.com/
to see if its worth bothering with the 4K version.