I am considering selling some of my established websites. I would like to get a third party appraisal for the value of the website before making a proposal to potential buyers. I have purchased the premium appraisal from sedo.com before and it is okay, but most of the factors they consider are Alexa ranking, PR, and traffic estimates. It doesn't seem to take into account actual or potential revenue streams, email list size or the many other factors that would increase the value of a site.
Does anyone know of a service that would provide a well rounded valuation of a website? Thanks for any suggestions!