Seeing as how the prices have been soaring, there was a frame/fork that sold for$860 recently, I don't think that's out of line, especially in SF.
It's more than I would like to spend, but if the condition was good and the fit was right, I would be very tempted.
If I was in SF I'd run (not walk) over with 10 $100 bills in my hand, and another couple in my pocket, in case it's as nice as he says.