One thing that I would point out to those who use GoValue estimates when talking to potential purchasers, the estimated values do vary significantly with time. I am not sure whether this is because they are constantly tweeking their algorithm, or if it is because of undue influence of new sales data added to the database. It is not unusual to find a domain name that is $400 one week become $1100 two weeks later, or vice versa. Estibot on the other hand seems (maybe too!) stable unless the actual exact name has a new sales record. I have checked a few names about a year ago and now, and all but one remained exactly the same value (and the other only changed slightly).
I agree with those who say that generally (the estimates) are too high, but there are also cases where they are too low, and as I pointed out from my analysis of NNNNN com sales and GV estimates, on average they were correct. By the way if anyone is doing similar analysis it is critical to check GoValue right after the sales announcements to make sure that the sales themselves don't influence the valuations.