Kelly Blue book reflects asking price / apprased value at a dealer, and generally lags several months behind the market and runs somewhat higher than the prices people actually pay. They gather the data by basically asking dealers "if you had one of these, what price would you ask, and if someone came in with one what is it worth to you as trade in." That's why banks and insurance companies do not use this value. But sellers like to use this value, as it is usually higher than the actual selling price.
The NADA value is more accurate, as the data is gathered by dealers reporting what they actually sold a bike like this for in the last 30 days. They also list the low retail value, the average retail value, and the highest retail value, so you can see the range of prices people have paid. So it is a more accurate guage of what you would expact to pay for that bike.
The MOST accurate data is inthe NADA non-consumer edition, which banks use to determine how much they will loan you on a used bike or car, but that is not available to the general public. It has much more detailed additions and subtractions from the value based on mileage, condition, accessories, etc, that what is available either at KBB or in the consumer edition of NADA. For example, the consumer edition and KBB will just give an average amount of miles per year for a bike in a certain cc range (it may say all bikes over 1000ccs will have about 10,000 miles a year on them or something very broad and general like that), while the non-consumer edition breaks down with value adjustments up or down for each 1000 miles on the odo. But unless you own a dealership or have a relative that is a loan officer at a bank, you probably can't get the current edition of this.
In either case, you have to deduct if this is a private sale, because bikes are worth more if there is a dealer to inspect the bike before the sale and stand behind it after the sale.
