A free list of your target clients may be as close as you local public library. Or even you own home computer.
Check with your local librarian to see if they have RefUSA. Chances are they do and you can access it from your own computer.
Here’s a quick how-to on downloading one of these lists.
http://www.youtube.com/watch?v=4S18__cJTx0
And here’s another great list building resource from Tellman Knudson, titled, oddly enough…
listbuilding.com
Keep Rockin’