Dark Web Forum Research

My boss wants to hire an individual/company to review the Dark Web forums and markets to check if any company data/credentials have been compromised data.
I would appreciate any tips on determining if the professional offering the service is legit, providing the correct data, and what such a service should include and cost approximately.
Thank you!

boss check compromised cost credentials cybersecurity dark dark web data forum forums hire legit markets professional research review service tips web