Where to buy remainder books or preloved books?

Hello, everyone!! I'm currently trying to get back to reading physical books kasi medyo nananakit na ang mata ko kapag sa tablet nagbabasa. Unfortunately, 'di ko afford yung books galing nbs or fullybooked, and as much as possible ay ayoko naman bumili ng reprint kasi I think (correct me if I'm wrong) illegal sya and doesn't feel the same as the original copy. Kaya naman I want to know where to buy remainder books like yung mga binebenta ng nbs during holiday season or affordable preloved books. Thank you so much in advance! Help a book lover out 😔✋️