Well, that doesn't add up to me.
I get the Marin and GT part (larger manufacturers, Etc), not boutique, independent, handcrafted companies like the others you mentioned. But Salsa?
Not drooled over or drool worthy?
Judging by the big NorCal collectors and their collections, Salsa seems just as lusted over as any of the other builders you mentioned.
And Ross has to be one of the funniest, seemingly personable dudes in the industry... or was, when he was still part of it.
Weird to compare it to Bontrager, and negatively, when they basically go hand-in-hand, too...
As for the stem: I think they trade for just as high a value over here.
As I say, mine cost more!
Oh, and lastly, yeah, it's the motherland of MTB, but there is more to vintage mountain bikes than just what was popular in the Bay Area at the time. I say this as someone who loves bikes from that part of the world over all others, and finds that GT's especially leave me cold.
The reason people are drawn to different bikes from different places is what I think makes this collecting thing interesting. My assumption is that people's feelings towards certain manufacturers has a lot to do with distrubtion: either you saw stuff at your local shop or beneath the arse of a local legend and wanted the same, or you didn't and wanted it for the opposite reason anyway! Because it was hard to find and thus elusive.