A lot of people complain that ebooks are too expensive for a virtual product. After all, you can't resell an ebook to a used bookstore when you are finished with it, and most people assume that most of the cost of physical books has to do with the expenses of printing, storing, and shipping the books.
The New York Times put out an article that does the math for us, and in actuality, printing costs aren't as high as you think.
Math of Publishing Meets the E-Book
According to this article, printing, storing, and shipping the average hardback only costs about $3.25 (so it would be even less for mass market paperbacks). And there are many other expenses than printing to consider. There is the author's royalty (usually about $3.90 on a hardback, $2 or $3 on an ebook) and the cost of marketing. Also, don't forget a lot more people than just the author collaborated on the book — the publisher also pays cover designers, editors, etc.
The article breaks down the specific costs better than I do, but suffice it to say that when people complain about all the money publishers are saving with ebooks, they aren't considering the many costs other than printing and shipping that are associated with publishing books, even ebooks.