Take the famous quote, "The best things in life are free" and portray a photo of it. A breath of fresh air, sitting in a park or just taking a walk would be good examples. Obviously. materialistic items, "Computers, cell phones, video games" are off theme but try to be as creative as possible. Scenery is off theme if the scene is the main focus.
There has to be another primary focus if there is scenery in the background. This contest is open for many different interpretations, but if it's not obvious, make sure to mention in your description what good free thing/feeling you're trying to show with your photo.