How to Sell News Footage
Item 1: A large number of network stations also get CNN footage. If you sell your footage to CNN first the other co-ops may not be as inclined to buy it since they will not get as much affiliate demand since their affiliates are already getting it from CNN. (This logic applies to NNS as well I assume)
Item 2: You can sell video on a show by show basis. Good Morning America, Today, and WorldNews or whatever. You do not have to sell footage on a network wide basis. For the really right stuff $5,000.00 per show or network is not a crazy number.