Black book prices are what an auto will sell at auction and can very, this data is used by dealers so they want pay to much for a trade. The average auto sales lot will markup an average vehicle for about $2500 over what he paid for it. But, he will need to detail and fix anything that may need to be fixed before it could be sold, ie, tires, brakes, etc. Now what happens when you go to trade a vehicle in at a dealer, the used car department will value the car using Black Book pricing and adding condition of the car and mileage will usually means a reduced value for your trade. The manager will use this to allow a trade-in value, also he is trying to find a buyer who will pay more for the auto because they really do not want to go to the auction. It cost them...this is usually what adds the most time to negotiating a buying price. Good look...Boxsters can be bought at KKB trade in prices.