Buying the cheapest book required consideration of many factors, such as the time of publication, the publishing company, the type of book, and the region. Generally speaking, major e-commerce platforms and physical bookstores had promotions. You could follow their official websites or social media accounts to get the latest promotions. Other second-hand bookstores or online second-hand markets might also have cheaper books than e-commerce platforms. Before purchasing a book, it is recommended to first understand the market price and promotional information to choose the best purchase channel.