Actually, on that one you're in luck; I live in a non-English-speaking country, and even I can usually find Ender's Game in a used book store if they have any sci fi in English at all. Buying used takes a lot of the moral dilemma out of it -- for me, at least; it makes it less of a 'how does it affect the writer', because he'll never really feel it even in that tiny way, and more 'do I want this thing to live in my brain'. Of course, someone else who can't find the used copy you bought might then buy it new, but that's a bit too advanced for me...

(I'd suggest yes on that last part, by the way; it's a very interesting book.)