How much do "experts" in the legal field, medical field, etc. get paid to do guest spots on news programs?

I am talking about on news channels like CNN or MSNBC, when they have guest legal or medical experts on who give their expertise on court cases, medical discussions, and stuff like that. I don’t mean celebrities like Dr. Drew, I mean regular lawyers or legal experts, doctors, psychologists.

I figure they have to be compensated for at least a few hours of their time, which could be a few hundred dollars per hour, so would they get a few thousand? Five thousand?