I switched to apps and ebooks nearly exclusively upon obtaining a high-quality iPad. I'm a big fan of pretest, and their app costs as much as buying each book new at full price, but allows me to have it anywhere and work on its questions with no flipping and page-marking: end result I get it done. I like carrying and reading on the iPad and do it more than I would if I needed physical books, so I have gotten several texts and reviews in Kindle format and have been very satisfied. You can't catch a deal on the old edition nor can you resell, that's the downside, but my convenience is worth some money to me these days.