This is off-topic, I guess, but I wonder why they always have The Dark Knight Returns Part 1 and don't have Part 2. They do the same sort of thing with the Amazon Prime Video for some reason. I guess it might encourage you to buy/rent one at full price and get the other cheaper/free but it still seems odd. I think you can get the German deluxe edition for about £10 anyway, which might be a better option if you don't mind the box being in German (and if you don't feel compelled to have the two parts as separate films).
On the subject of The Dark Knight Returns, I thought I wouldn't like it since it features older Bruce but it turned out to be quite awesome and is a strong competitor for my favourite DC animated film (also DC film in general but I guess that might go without saying).
(Just so this isn't entirely off-topic) I think Tekkonkinkreet is one of the few anime films available in the UK that I haven't got in some form, is it worth getting?