But wait, there’s more. Much more. We generally encounter four different acquisition models (my thanks to Janet Morrow of our library for this outline): 1) outright purchase, just like a print book, easy peasy, generally costs a lot even though it’s just bits (we pay an average of over $40 per book this way), which gives us perpetual access with the least digital rights management (DRM) on the ebooks, which has an impact on sustainable access over time; 2) subscription access: you need to keep paying each year to get access, and the provider can pull titles on you at any time, plus you also get lots of DRM, but there’s a low cost per title (~$1 a book per year); 3) demand-driven/patron-driven acquisition: you don’t get the actual ebook, just a bibliographic record for your library’s online system, until someone chooses to download a book, or reads some chunk of it online, which then costs you, say ~$5; 4) evidence-based acquisitions, in which we pay a set cost for unlimited access to a set of titles for a year and then at the end of the year we can use our deposit to buy some of the titles (<$1/book/year for the set, and then ~$60/book for those we purchase).

OverDrive: Ebook Checkouts Up 33 Percent