Agreed that a price guide for bikes is a different sort of problem than for collectible guns or watches. Mike, I think, mentioned how many more bike makes there are, even compared to watches. But unlike guns and watches, for example, a bike frame is encrusted with a coule dozen other potentially collectible that each have their own highly variable collector value and their own highly variable condition.
Even though guns can be reduces to components too, and occasionally someone might collect a gun in order to use a part off of it for another collectible gun, this is rare compared to bike collecting, and guns tend to stay as whole items and not get parted out. (There are a few exceptions to this, but it's rare that someone sets out to build a gun from parts, as we all do all the time with bikes.)
Same for watches, even though someone might by a trashed Omega for it's properly labeled backplate destined for another Omega that has the wrong one. Still, there is nothing like the propensity for this like there is for parting out bikes.
Given an immense amount of time, one would could produce a price guide for frames/forks, and for each component type, including the oft mentioned 1st gen S.Record rear der. The situation where one enounters a original complete bike that can be valued all as one thing, and whose condition can be assessed holistically is more rare. We tend to talk about these, though, the recent Masi vs. Herse racer thread, that lovely 1968 Pogliaghi that recently switched hands on list via ebay. When less stellar bikes are offered whole, they get looked at not as a bike for sale but as an assemblage of bike components for sale.
Little Rock Canyon, UT