Should I try to sell my 2004 Ford Mustang or should I let the leasing company take it back?

blue_prince_of_dallas asked: I leased a 2004 Ford Mustang and it is time to give it back to the leasing company or I could buy it from them. The online Kelly Blue Book estimator said it is worth $11,650 if I try to sell it to a private party and it estimates a Trade-in Value [...]