I’ve seen good sites loosing all their values because Google started ranking them lower than usual. This also happened to me.
One of my communities had almost all of it’s pages in the top 3 for many good Google searches during many months. When suddenly next Google update (we call it dance) came, they went to the second page. We didn’t do anything.
So how will you value a business based on your current rankings? You never know where it will be next week. And if the rankings go down, the profit will also go.
So I would never buy a business based on those attributes. I would buy something I “believe” I could upgrade for better use, using it to improve my existing business. This is what Google, Yahoo and MSN do.
The keyword here is “believe”.