The information on a business email list is highly valuable. You should not be surprised that it has become increasingly hard to buy. You think drugs and firearms are the only business under regulation? Do not underestimate the damage criminals can do with contact information.
As a matter of fact, unlike phone numbers, what you see as a list of email addresses is a safe full of passwords in the eyes of hackers and other cyber criminals. Give enough malicious intent and determination, even average hackers can put together something dangerous to exploit that list.