Digital tech books, where are you?

Why are PDF/CHM-versions of many (most) tech books so hard to find? Perhaps I’ve just missed the store that sells them? Digital versions are so much more convenient – they’re always along on my laptop, and they can be searched easily. Yet even O’Reilly’s site doesn’t sell the PDF versions. Yes, there is Safari, but I don’t want to have to read them through my web browser. First, network connection is not always available (customer locations, etc.) and secondly I don’t like Safari’s pricing. I simply want to be able to buy the books I need, and have access to them at all times without a monthly fee. After all, if I buy a print book, that’s the way it works — except that I have to lug the physical book around.

I believe the reason for why they’re not more readily available is the fear that they would be more easily illegally duplicated, yet it’s apparent that most any book does already exist in electronic format. So why are they not sold; would the loss of revenue from illegal copying really exceed the increase in revenue from people who would buy more books into their electronic reference library? Fortunately some publishers already include the electronic version along with a print book, for free! For example, the recent editions of Wiley’s JavaScript Bible have included a CD-ROM/DVD-ROM that has included the same book in electronic format along with the code examples for the book.

If someone reading this knows of a web-store that has a good selection of PDF/CHM format tech books for sale (O’Reilly, Wrox, etc.), I’d like to know!