Minecraft wiki entry for Enchanted_Book, associated text: In Bedrock Edition, librarian villagers have a 50% chance to sell enchanted books as part of their trades at novice, apprentice, and journeyman-level, and have 1⁄3 chance to sell enchanted books at expert-level as part of their trades, meaning each librarian villager can sell up to four books. They are bought for 1 book and 5-64 emeralds, based only on the level of the enchantment (for example, Infinity and Protection I both cost 5-19 emeralds), although treasure enchantments (such as Mending) double the cost.