Where Are The Untapped Seller Financed Mortgage Notes?

   I guess the county recorders office is the best location for untapped seller-financed notes. I've tried several mailing lists and other online postings which all seem to be wrung dry. I do love this business but i'm wondering if this business is in the Billions yearly where are  all these notes? Is it just restricted to those who have years upon years of experience, or maybe it's only for banks and insurance companies to enjoy?