Hmmm.......I wouldn't mind free access to the NEC. After all, it is a safety document that should be readily available.
However, I think a lot of untrained people would have trouble understanding and using the NEC.
On the other hand, I would support all the NEC rules that pertain to residential situations available in a "cheap book" that you speak of. Said book would have the NEC rules followed by an explanation of them, much the same as Mike Holt's "Understanding the NEC" series.
I agree, many DIY books are suspect or just downright bad. I love the ones that show you how to strip solid wire with a pocket knife.
The only DIY books that I can recommend are Black and Decker's "Advanced Wiring" and Rex Cauldwell's "Wiring a House."
Someday, I would like to go to Borders or wherever, buy every DIY book on the rack, and highlight all the errors that I can find in them.