The costs of selling books can vary widely, and a lot of them depend on your goals. If you want to just clear out your bookshelves, your costs will be limited to marketplace listing fees and shipping. On the other hand, if your goal is to start your own website, you will need to consider costs like a domain, hosting, inventory, shipping, and marketing.  It’s a good idea to start small, track your progress, and make informed decisions as you grow.