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...I'm in the SF Bay area, which I've always considered like the mythical elephant graveyard for really high end steel bikes. There are fewer of them appearing now and over the last couple of years on the local CL. I check it out every now and then, and the high priced stuff that shows up tends to remain up much longer (because it really is overpriced in many cases).

I attribute it to the length of time that has passed since people were making and selling them new. IMO, the supply is gradually decreasing as they die or get lost in the downward spiral of use and abuse. They're still around, just in fewer numbers.

In a strange twist, the prices that people seem to be willing to pay for them seems either stagnant or dropping. I attribute this to a general shrinking of the user and owner demographic, as the money in the "serious" cycling community all goes to plastic. I could be wrong.