My domain blackberryvids.com is valued at $659 on dnscoop. It's only a Pr1. The domain itself has been live for almost a year. It was live 8 months ago and I shut it down. I re-opened it last month and it was valued at $12. In a month I got it up to $659. If anything it can be used as a means of seeing how my site has grown. I'm hoping to get it to $1000 by the end of the month. It's possible as my search engine traffic has been increasing dramatically over the last few weeks.
Frankly speaking,those auto domain evaluator is unreliable. I have a site that valued at $16893 with less than 100 unique/day. So,if you plan to sell your domain based on the value. My advise is think again.
Like i said I'm using it as a means of evaluating my performance some what. When I see that they are raising the value it shows that I am doing better and it also can be seen in my analytic stats to support it further.
^ For better analysis you should check the stats using different tools such as statcounter/awstats and google analytics.