Here is how to get hundreds of target email addresses in a short time without spending anything.
First, identify, by X-Raying the contact database https://rocketreach.co, companies with a 100% format use. In my case, it is Healthcare companies in NYC. After I scrape a list from a Google search, it looks like this:
Now, if I know that someone with the right job title who lives in NYC, has over two years of experience, and works for one of these employers, I need to only have their name to be sure that I can reach them by email.