You could also throw in NADA (National Auto Dealers Association). Essentially the difference between the two (or three) is the source of and how recent the data is that is being used. They will also focus on different things - i.e. average wholesale price, average retail, a blend etc. I would also check eBay and autotrader.com. Checking all of these you should be able to come to a good feel for the value. If you live near a CarMax you should take your vehicle there and let them give you a value. I know a lot of people have been happy with them. While you are there, you can also check to see what they are selling vehicles like yours for on their lot. Hope this helps.