So after years of holding on to dreams and withstanding temptation, I've decided to part way with some or most of my collection of books. They're mostly non-fiction, but I'm wondering how people calculate the prices when selling their collection to a another collector or wholesaler. Would your formula change from small numbers to big numbers? Looking for a variety of perspectives, but it is the debate room, so feel free to disagree. ETA: In case you're wondering, the books are mostly printed 1950-2000, both texts and original author, classics and crap, a grab bag. ETA: I've set up a meeting with a buyer, and am reasonably comfortable with my formula, but want to field the question.