I use Linkedin, Company websites and Google search for this work.
Although it depends on industry and search terms but normally i can deliver between 400 to 650 emails in a day. We are a team of 10 professionals to do this work.
It takes around 1 hour to search 12 to 15 emails, So it will cost around 35 cents per email.
final work will be double checked and properly formatted in Excel File/Google Docs
Email search and List Building
Email search and List Building with in 24 Hours