In the UK it's always worthwhile logging music book requests with Travis and Emery at Cecil Court in London. They're specialist music book dealers and will keep requests logged for when books come in (That's how I got my old copies of Chappell several years ago - they phoned me about 6 months after I'd made the request to say they had a copy in). I've got several good folk related books from them and always have a look in when I'm in London.

Mick