"I find myself seeking along the lines of reference vice inspiration so to speak. A good deal of manuals these days are shear repetition of what is already out there, albeit at a later date in time. With the advent of the Internet and forums, I find myself more and more building a reference library from great articles posted from learned enthusiasts, rather than purchasing books these days. I don't know who is to blame the author or the publisher. It often seems that many given references have excellent content only to be diminished by what I deem "filler material". Hence another reason for building a reference library out of specific articles published by reputable practitioners vice buying books."
I haven't bought a bonsai book in a couple of years, aside from the republished Lenz book--which is worth every penny. Unfortunately, the bonsai book market favors entry level, since that's basically where the mass audience and money are. Good, in-depth, advanced bonsai books are very rare.
I keep hoping someone will take up the huge challenge of equaling Nick Lenz regional book for other parts of the country--like a SouthEast book that covers bald cypress, tupelo, live oak, etc. A Western version that covers species from there, and so on. Those publications would probably have an extremely small readership and would be losers financially though...