Freakonomics: prices of used bikes and cars inversely correlated

True, but the author is looking more at run-of-the-mill 2nd hand bikes, not collectables:

Yeah, the bike guy answered, he had something super-cheap for me, an old road bike that they’d fixed up. It wasn’t exactly my size, but it would do. It was a 1991 model, a Trek, I think. It was in good working condition, it had some newer components, and it came with a warranty. I could have it, he said, for $475.