If you have any suggestions, I'm always willing to hear them. But no, there is no way to square the hypothesis that I've depleted prospects available with my current marketing channels when the sales chart keeps going up and to the right.

Organic SEO (and by extension AdWords) is like a river: water goes by today, either you get it or somebody else does, but there will be water tomorrow. The total market is far, far larger than my capability to service it. (There are 3 million elementary schoolteachers in the United States. I have 3,500 customers.)

The nice part about email is that it lets you "store water" if you follow the analogy, since loss to evaporation is just obscene in my business. 80% of people who signed up last October never logged in again after 48 hours from their signup. Many never logged in a second time.