I have a super crappy laptop currently mining Hobonickels, but would like to earn more. I will vanity mine addresses for you, you can define the price and pay me after you verify that it works.
I think that you won't get more coins by doing so than you do by mining.
1) People would pay proportionally to what the computing effort required to find the addresses would bring by mining bitcoin instead, and no more than that.
2) People would actually pay less than this upper bound, as there is a risk premium because they have to trust you won't keep the private key of their address.