How do you determine the marketability of your tickets: 

The first thing you must find out is the "face value" of your tickets along with any fees that may have been added to the price of the ticket at the time of purchase.  Then you search websites to find out what similar seats are selling for.  Sites such as CraigList.com, StubHub, Ebay, and Razorgator are several high traffic sites that will be able to give you that information.  Even the length of time before the sporting event will determine the marketability of your tickets.