The shipping price accounts for packing materials and other resources such as time spent on packing, creating the post on eBay, answering questions, driving to the Mailing post office, etc. It is also used as a base minimum price, combined with the minimum bid offered a such low starting point, to sell the book. This offers better transparency to buyers instead of adding a "auction reserve price" to be met by bidders and risk having a "reserve not met".