Most hackers for hire are found on Reddit-like forums. There are a bunch of them, and you have to know where to look. But these hackers remain anonymous, offering certain services, and demand decentralized payment.
One post on an underground hacking forum claims it will "Website hack or ddos. Paying well." The poster explained that they wanted a WordPress-built website down. While this person would not provide reasons, he or she did add that the bounty was as much as "2k euro."