It's actually really easy, if you have a budget that is reasonable and you have an expert who can deliver! Any scraping software is going to refer back a lot of junk in with the contacts you need. Problem is even if you use a mass mailer software your emails will have a horrible bounce rate and your email / IP can get blocked depending on how you send the emails.

There is a reason software is cheap. There is a reason Experian charge a fortune for quality data. Because it's worth it.

Building a quality email list of your own is the way forward. It doesn't necessarily take that long to start building a nice list.

There are also other ways to attract the clients you are looking for - content marketing for example.