I read through this string yesterday, thought about it a lot and am still, apparently, not getting it. Why are you trying to sell clients on the need for grantwriting services? You have a huge market among organizational E.D.'s who already know the benefits; they are just looking for the right person.
I see it this way: an entrepreneur sees a need and fills it. A marketer convinces potential clients/consumers of their need for his/her goods/services. Your community cannot possibly have enough good grantwriters to go around. I can't imagine that you would even have time to "market" your service.
Where are the savvy, up-to-their-eyeballs-busy NPO E.D.'s in your city? They are the ones who can't wait for you to call and tell them you're coming to the rescue.