We currently use blackbook on our site. It provides a pretty fair amount of quality leads. We are going to switch to KBB, not due to lack of satisfaction with blackbook, but to see if we can generate even MORE leads. The way we view it, KBB is more of a brand name to the consumer, that is the name they are comfortable with. They will click on it becuase they know it. Blackbook, is not near as branded to the consumer. Kinda like carfax. To the avg consumer, carfax the THE source to get a history report on a car. They don't have a clue what Autocheck is. If I offered my customer an Autocheck on their car, they would think it was some sort of jicky dealer report to make the car look better.
In terms of using your own appraisal type tool, it COULD be something that would work. I am sure that there are disclaimers and everything that doesn't hold your feet to the bid, but as soon as your name is attached to appraisal tool, you are beggin to get in to a showdown with a customer over why you can't give them the value they got from your tool. We all know how to over come the objection, but it will still, inevitably leave a bad taste in their mouth over the situation.
I guess we will see how the KBB experiment goes!