On the other hand, for fundamental subjects like math or CS algorithms/foundations, the difference between the newer and older editions of a text are not always very significant. University textbooks can be pretty egregious in this regard - some authors (who tend to be professors that use their own book for their courses...) just add a new foreword and maybe a new chapter, or slightly rework the homework exercises and release a new edition. So students need to buy the new $100+ edition, instead of getting a used copy at 50% of the price.
For more cutting-edge technologies, it does make sense to buy the latest and greatest. Although if it is something that is rapidly evolving, you may still be better off relying on the current documentation on the web - the lag time involved in writing a book can make it difficult to keep up-to-date as things change.
For more cutting-edge technologies, it does make sense to buy the latest and greatest. Although if it is something that is rapidly evolving, you may still be better off relying on the current documentation on the web - the lag time involved in writing a book can make it difficult to keep up-to-date as things change.