You are right- Estibot is one of the few to look at the keywords and consider the potential of the domain name. The others posted here seem to just go by traffic the search engines can see. I have blocked a few folders at my sites, including the forum, so I know they don't see the true traffic even..
The value (like in all other things) is in the eye of the buyer.
There are some site valuations that do indeed incorporate the income per month (etc) but most need that information tp be input by the user...so the honesty of such input comes into question.

I do not work here, but the benefits are still awesome
Make your sound your own!