FWIW, I bought my M4 two years ago from Ken Hansen for $1175. It was in terrific shape, although I had it CLA'd by YYE since the service history was unknown. Prices have definitely gone up since, but the M6 has skyrocketed. I haven't seen a decent one for less than $3000 in a long while.
Re: Camera West, that was mentioned in this thread. They are definitely legit (the owner also owns the Leica Store in San Francisco), but I've had mixed experiences when dealing with their internet sales person who is in the Rancho Mirage location. Not very responsive either before or after sales. They do often have some decent stuff, though. I've visited the Walnut Creek location in person and the people there are friendly and knowledgeable.