Actual transaction prices? Ebay obviously. Reference completed auction prices only, as a lot of Buy It Now Ebay product is absurdly overpriced, and sits unsold for years.

And uncompleted auction prices are no indication of final sale price, as no Ebay bidder who knows the first thing about auctions bids with greater than 10 seconds left in the auction. So bid prices with 5 hours to go are usually a fraction of ultimate winning bid prices. On larger dollar items, shill bidding is rampant; only sniping defeats the shills.

Why are Blue Book prices unreliable?... I find them a very accurate reflection of used bike value. I know there a lot of bike flippers on this forum who whine about their 1975 Schwinn being assessed at $50, when they think it should be selling at $500, but their opinion is pure self interest.

The bottom-line reality is a bike loses 30% of its value the moment it exits out of a bike shop door, and a 5-year old bike, no matter what the condition, is worth no more than 50% of original sale price.

And that very very few bikes (maybe 0.0001%) are worth the nominal dollar value now than when purchased in 1975. A mint condition top-end Colnago, Cinelli, Pinarello, etc. But that is about it.

Finally, used bike prices vary widely around the nation. Generally coastal states that voted Dem. have the highest used prices. So a beat-up Bianchi fixed gear that you couldn't give away in the Midwest will attract big $$ in hipster burgs such as Seattle, Portland and SF.