iTunes/iBooks have lots of batman comics/collections of £1.99 including...
The Killing Joke
Court of Owls
Dark Knight Returns
And a few others too.
Most likely due to the 75 year anniversary? So I'm not sure how long this deal will last.
Fairly new to the batman comics so any recommendations from these would also be great to hear!
Link - https://itunes.apple.com/gb/book/batman-dark-knight-returns/id553035914?mt=11