We're not exactly drowning in questions these days, and there was general consensus that business questions are on-topic, including your example then of "a magazine wants to buy a photo, how much should they pay?".
But I agree that it's unlikely that we'll be able to provide a specific right answer to this sort of question. Maybe we can have one "how should I price my photo" commuity wiki question, and refer new questions along those lines to that one.
These questions have a place and even if no direct answer (or even a price range) can be given, it's likely someone can point the person asking in the direction of an answer applicable to his location and customer/usage.
Such information can be hard to find, there's no www.pricemyphoto.com website :)