I have a 40 minute period long Market place role play that I adapted from materials given to me by a
co-teacher.

 This includes the introductory power point, The item cards to print and cut out, customer Mission cards, the dialogue cards for the sellers and customers, and the name cards for the stores.

Basically the kids played in teams of four, switching between sellers and customers between each mission card. Sellers roll the dice twice to determine the price to write on the mission card. When finished with a mission a group would come to the front of the class to turn it in and get the next one, then go back to their table to switch places with their other teammates.

I played it as lowest total cost wins, but they also made it a race (without the instruction to do so) so I awarded the first group to finish mission 6.

You need dice for each group/store.