Considering the work that goes into databases like that, and their high profitability, I think you will have trouble finding a cheaper option without doing lots of leg work yourself.
Personally, I sort of like that mailing lists cost a chunk. I get enough junk mail even at high prices. I shudder to think what would happen if the info was available cheap and easy.
directmail.com
Many title companies can provide you with a list of non-owner occuppied properties by zip code through their property information departments.