I was fortunate in having a boss with current copies of both the "Illinois Manufacturers" and "Illinois Services" directories which, along with the Chamber of Commerce membership roster, became my database. I'm not sure if the publisher of the Illinois books offers something similar for every state, but I did find the following link to something which looks like it fills the same need:
I have worked with purchased lists with not nearly as much success. Creating your own database versus buying one is analogous to baking your own lasagna versus settling for take out!
