I loved running a classroom economy in my class. Students were presented with a list of jobs that they could apply for. Each job paid a different amount of money (just like in the real world). They needed a job because I charged them rent for their desks! Each desk had a different price. The ones toward the front of the room were more expensive (prime seating!). Students got to sit where they wanted. Each month they needed to pay rent to continue sitting where they wanted to sit. If a student couldn't afford the rent, they were evicted and had to sit where I told them to sit. If a student saved up 3 months of rent, they could buy their property and call it a condominium (put they had to pay property tax).
Each year I had a different theme for my desks. One year I did islands of Hawaii. Another year I did countries. Last year I did cities in the US. Each group had a sign that said what it was. This was a nice detail!
Our classroom economy exploded! I had students decide to make their own shops to make more money. They even hired employees to work for them. Talk about entrepreneurs!
Students kept track of their money in their check register. Each quarter I would do special activities (movie parties, class parties, restaurants) in which they would need class money to participate. Students and parents loved this!!!