PsychoGemini, nice up and down game! I've taken it and created another version for a whole class individual game. The way it works is:
1) Give each student a points card (check the jpeg file)
2) Let them see the price and have them guess if it's higher or lower. If they think it's higher, they should stand up; if they think lower, stay seated.
3) After they make their decision, reveal the price. If it's higher, whoever is standing gets a point; if it's lower, whoever is seated gets a point.
4) Play the game for 12 questions. Winners or those with a certain number of points can get a reward with whatever system you might use.
(I plan to use this for the first listening period and have the students repeat after me e.g. "How much is this toy car?" "It's $5." For the second period, I suggest that you use an effective speaking game/activity.)