Actually I'm coming from the good old days, so fakes are no issue for me. I guess one day I'll write a short-story book about what really happend in the watch market, including the confidential stuff I got by accident from JLC. Muahaha.
Take your AM 6b/159 for example guess where it comes from... Found on Ebay, sitting there for ages, bought it, lost interest due to wrong hour hand e voila, its with you via a DC fellow. It is a small world indeed. 
Some Artcurial results are rediculous as for other brands Antiquorum or Sothebys results are. On the other hand for some very limited stuff it sets an idea, since the stuff is so rare you won't find any compareable pricing.
Sometimes, my dear friend, it is a gamble to buy a watch blind. No risk no fun!
Cheers,
Ilja