Anyone know about Business lists sales?

Has anyone worked for or know anything about the "Business List Business" where you purchase lists of valid contact info for doctors, lawyers or other professionals?

I need a quality source and am new to this area. Seems lots of these company's are frauds and whatnot.

Chime in if you have had good experience or worked for any of them.

I've got lists for those professionals. Let me know if you're still looking...

Check out my AngiesList scraper thread: http://www.blackhatworld.com/blackhat-seo/member-downloads/448120-get-free-angies-list-scraper-2.html
It can get you tons of leads for any industry/location. Business Name / Number / Owner's Name / Street Address / City / State / Zip / Website / Email, all in one nifty file that you can open in Excel.

Also, I'd recommend taking a look at my YellowPages scraper thread: http://www.blackhatworld.com/blackhat-seo/member-downloads/450143-get-yellowpages-scraper.html (now supports UK as well!)
Not as many details to scrape, but still Biz Name / Mailing Address / Phone Number / Website
These are both 100% free, and always will be.

Seriously, don't buy lists. I make scrapers almost daily for various business directories, and seeing as every business that has marketing as a priority AT ALL will be on there, there's no "secret extra listings" that a broker can offer you (that will do you any good, that is).

There's several legit list providers. http://www.infousa.com/ is one that I can think of off the top of my head. I don't know about businesses, but with personal mailing lists you can get very picky about the type of demographic you want.

If you're just calling a few of them up or whatever, just use the online Yellow Pages or something to that affect.