Yes you'd think there was more interest, but perhaps it's also these economic times. The price is OK, but out of my price range. I certainly compliment you on the book though. It is a topic worth much consideration. For one it is colourful. For another it is most relevant to traditional or folk music since it has roots going back probably as long as there's been street music.
Perhaps it's in the book, but I saw a postcard some years ago with a picture of an unusual one man band. The man was sitting and playing a guitar, and in front of him, with the mouthpiece at lip level, he had a tuba on a stand with an attachment to operate three valves by foot. I'd very much love to hear that.