I don't think that the Shimano components were swapped out by this guy: I think he's a second or third or fourth owner. He didn't even have the brakes centered and adjusted, and seemed to know pretty little about what he had (didn't even try to sell it much, and obviously didn't realize that it wasn't actually a 400.)
I'll wait and see, maybe I'll get an e-mail from him in the next few days, but I kind of doubt it. I think enough people know the Trek name without actually knowing much about the bikes/models, and I think that there's always someone here in NYC who doesn't care that much about the price.
We'll see.
Meantime, I'll go looking for another.
Thanks for the support--it was hard to hold firm!