How is the sports card trading business doing in these current conditions?

I only need answers from people who know please. I'm not talking about looking into a magazine or getting cards appraised. What i am asking is how the actual "business" or the need for cards are these days. Do you just put a card up for sale that you have valued from a book and wait to see if there is someone interested? And also, is there an equal interest in different catagory of sports cards? As in football, baseball, basketball. thanks, and again, would only the people who know the facts answer please?