Hillary's spymaster was a former director of the Clandestine Service for the CIA in Europe. He now owns his own private intelligence firms. These are not the sorts of services purchased by poor men. These are the sorts of services purchased by very, very rich men, and big well-capitalized corporations, and even governments.That's not true, actually. They're often provided for free. If you're providing free intelligence to the Clinton machine, it's with the expectation of a quid pro quo somewhere along the way. But if you're providing it to the Secretary of State, it might be for patriotic reasons entirely separate from remuneration. Say you happened to be in position to know something important, which could really help the US government get something right. And you happened to have the right personal connections -- not directly, but you knew someone who knew how to get it in Madame Secretary's daily reading list. You might very well pass it on.
Private intelligence is often a business expense, not a profit-making venture. Sometimes it's a necessary condition for protecting other business interests, especially in places like Libya. Passing on what you were collecting anyway may not require any payoff.
Sometimes, the whole thing is a purely patriotic volunteer effort from concerned citizens who just want to help hold the world together. The people I've known from the Clandestine service have been extremely patriotic, which is no surprise since they are selected in part for that kind of deep personal commitment to the good of the nation. They already have networks from their days on the job. Sometimes they pass it on, even after they retire. Maybe that's the case here and maybe not. The Clinton machine has a well-deserved bad reputation. That doesn't mean they don't know people who are better people than they are.
All of that is to say: you can try to follow the money, but there may not be any money to follow. There may be favors instead of hard currency. There may be nothing to follow at all. It might even, conceivably, have been done for all the right reasons.