Price $0 (assuming you can find a soccerm / basketball / football or something)
Usually I play with 3-4 people otherwise it gets a little easy. All you do is find a roof that is a bit over your sight line (a roof where you can't see the actual roof when standing within 6 ft of it or so. Before the game, denote the boundaries on the roof on the left and right. Try to make them somewhere around 20 ft or so (the size of a two-car garage roof). Also, decide an order of who will go after who. One person starts by throwing the ball on the roof. The next person goes by throwing the ball back on the roof while not touching the ground (jumping in the air). Basically you try to keep the ball from touching the ground, by going in order, and jumping in the air every time you play the ball.
When a player screws up, they get a strike. After 3 strikes you are out. Simple? Trust me it gets to be pretty fun once people start figuring out how to get people out. Also, playing with a football makes it a bit more difficult if you think it is too easy.
Cheap and fun things to do around Minneapolis/St.Paul