Alright.
>a resource related to search engine optimization with the practice of back link marketing.
Back links and therefore back link marketing are only a piece of the full pie of SEO.
>to be developed as a database set to help those optimize with data provided for online marketing purposes.
So your buyer would need to be someone interested in creating a directory highlighting back link marketing.
In other words specifically interested in creating a directory (nothing else) specifically for back link marketing
(no other aspect of SEO). See how your potential buyer base just gets smaller and smaller?