95% of my book purchases- novels, textbooks, RPGs, CDs etc.- I buy in my local stores. The same goes for my other purchases. There are many reasons for this.
1) I live in the Dallas area- if a book exists, odds are good that I can get it that day.
2) In my work as an attorney, I've developed a distrust for online commerce. Sure, most transactions go through just fine, and most databases are secure, but I've handled enough ID thefts (due to misdirected transactions or database hacks) and fouled-up transactions that were more difficult to deal with than similar problems I've solved talking to local managers that I simply don't care for online shopping all that much.
3) It serves as a speed-bump for my purchases. With my credit and my tastes, I could easily see myself going on shopping binges for books, guitar pedals, obscure recordings and all kinds of things if I didn't consciously limit my online purchases...thus ruining my credit!
About the only thing I do buy online is the occasional extremely rare CD, or things that are simply not available in any other way- direct-sales guitar pedals or specialty picks, unique jewelry options, and so forth.
The advent of the new e-readers may change some of that...though less for me than for my Mom. Her eyesight isn't the best, and she likes those read & forget thrillers these days. That means she has to buy them as hardcovers for the print size...and then try to sell those except the few that she wants to keep. Electronic copies, with their resizable fonts, may be the solution for her in terms of print size, storage, and the like.
I don't see myself buying e-books for anything I want to keep, though, except possibly as duplicate RPG books for a precious few games. And I don't forsee that happening for some time.