VUDU has Digital HDX/4K UHD Films on sale for $4.99 each.
Example Films (movies marked as MA are Movies Anywhere Compatible):Straight Outta Compton (4K) (MA)American Made (4K) (MA)Hell or High Water (4K)The Last Witch Hunter (4K)Malcolm X (MA)Prisoners (MA)Batman: Mask of the Phantasm (MA)Strange Brew (MA)Spawn (MA)Roxanne (MA)In the Line of Fire (MA)The Big Red One (MA)Get On Up (MA)Smokey and the Bandit (MA)Love and Basketball (MA)Boiler Room (MA)The Last Airbender