Most North American journalists will tell you that it's unethical to pay for an interview. So, officially established news outlets never do it. In reality, they do pay. Gawker explains how this works: News outlets claim to be paying for the rights to a photo of the subject, with the tacit understanding that buying a picture will lead to an interview.
According to Gawker, Flight 253 hero Jasper Schuringa made about $18,000, ostensibly by selling some lousy photos of himself to CNN, ABC, and the New York Post. In fact, the photos were just a fig leaf. Schuringa was reportedly quite upfront about the fact that he would only talk if he got paid. I don't begrudge Schuringa the money. If anyone deserves a holiday windfall, it's that guy. It's not his job to uphold media standards.
That said, media outlets shouldn't pay for interviews. The practice creates glaring conflicts of interest, real or apparent. Journalism is supposed to be about finding the truth, not bribing people to say what you want to hear.
That said, if a news outlet insists on paying for interviews, it should be absolutely transparent about doing so. We should at least know that a source was paid for their appearance. These days, if a blogger gets a free review copy of a book, they have to include a disclaimer to that effect in their review. Yet, CNN doesn't feel obliged to tell us that it landed a Schuringa interview because of deep pockets rather than journalistic acumen. CNN, ABC, and the New York Post should join their media counterparts in the UK and admit that they pay to play.