Specialized gets my vote for most overvalued. I own a Specialized. The newer versions of my bike have lower level components and the price is about $500 more than what I paid. It's like that all the way across the line. I realize costs go up, but do they really go up so much that changing the paint job and putting on lower-level components makes the bike worth more?

As for the most undervalued, I have to lean towards something like Douglas. I just bought a Douglas Matrix with carbon frame/fork, Dura Ace drive train and shifters, Easton wheels, and FSA carbon crank for under $2000. I realize that the frame is imported, but how many of them aren't these days?