For things like manuals, data books and those that are no longer sold I just search Google or archive.org for pdf copies. For other commercial books, the easi

For things like manuals, data books and those that are no longer sold I just search Google or archive.org for pdf copies. For other commercial books, the easiest thing is something like 1DollarScan.com which will tear open the book bindings and scan for you. Other approaches that worked in the past include 1) knew a family member who worked in a copy store where I could play with a fast scanner. 2) Some publishers like Oreilly's in the past let you get pdf copies for free or nominal price if you provide proof that you bought a paper copy. 3) I have scanner at home for small books or documents but it is usually too much manual work. But largely over the past 5+ years, I only buy DRM free pdf books. Many of the technical book publishers have sales throughout the year on their website where you can buy books at steep discount. I'm just a pdf book packrat :)