Oh yeah, I forgot to say one more thing. You can probably find your mailing list completely free at the library. Ask your local library if they carry the infoUSA database and how to get into it.
If they don't have it check out the library in Hamilton County Tennessee, I know they have it, (I am a member) they have a $25 charge for an out of the area 3 year membership (or close to that) and you can download files for free off of your computer.
I send a lot of clients to this thing, InfoUSA is a huge database, you'll love it.
Again, Good luck.