Street Outlaws: No Prep Kings is on Discovery by way of Pilgrim Media Group, a production company that boasts an impressive roster of reality television shows. Its flagship show is probably Ghost Hunters, which has run on various channels, including Discovery, since 2004.
Ghost Hunters features people from The Atlantic Paranormal Society, whose website claims they never accept payment for their services. If that’s the case, they’re getting paid by someone and logic suggests it’s Pilgrim Media. We can then assume that Pilgrim Media also pays the folks on Street Outlaws: No Prep Kings.