Zoe's Nano sized reward

At the end of last school year I was inspired by a neighbor (thanks Tracy) to create an economy in our home as a motivation to do chores. The currency for this economy would be Monopoly money(Mm) paid out for the performance of chores and collected for such menial things as eating, sleeping in a bed, swimming, watching TV. It got off to a slow start. In fact, Heidi spent one night sleeping on the floor because she didn't have enough money to sleep in her own bed. Our experiment in capitalism took on speed as the kids expressed their desire at the beginning of the summer for some high priced electronics. It was agreed that if they earned the requisite amount of Monopoly money the bank of Mom and Dad would convert that into hard currency using the current exchange rate and the desired item could be purchased. Zoe took on the challenge with gusto. She vacuumed, did dishes, did laundry etc... at $10Mm per task and this past week was able to trade in her $1800 Mm Monopoly for $180 cash and purchase an Ipod Nano. If you are savy enough to realize that is more than a Nano actually costs, it is because Zoe was required to pay 10% tithing and put 10% in savings before she could go to the Apple store.
As a testament to Zoe's zeal, as she neared her goal at the end of the summer she set up a beauty salon in her bathroom where she charged $10Mm for pedicures and hairstyling. She also set up a private detective club and charged $20Mm joining fee. In the end she almost sold her proverbial birthright for a pot of porridge when Heidi offered to give her the $150Mm that it would take to get her over the edge in exchange for free reign over the Ipod after it was purchased. Zoe bought into Heidi's ploy very easily, but Reed and I invoked a 24 hour policy that would allow either party to back out of the deal within 24 hours. Zoe was able to see the folly of the bargain she had entered into and backed out the next day.
So the Ipod was purchased. Zoe is no longer chomping at the bit to do chores for me and Molly and Heidi, well, their lack of motivation was exposed the next day when I asked them to unload the dishwasher and they both told me "Zoe will do it", when in reality, Zoe had already said no. I guess they are going to have to step up their game to get their reward.