Of course, most college students don’t buy direct from the publisher because they aren’t aware that they can and/or don’t know who the publisher is and/or prefer the all-in-one ease of walking into the bookstore and handing the clerk your schedule over tracking down each individual book online. However, if e-textbooks become more common, then it will become easier for the publishers to sell them directly, for example via the compare prices functions used in online bookstores. So even if the prices of the textbooks weren’t reduced at all and the e-books were sold at 100% of the print price, textbooks would still be functionally cheaper, since people would be more able to circumvent bookstores’ doubling of the MSRP.