If you want your kid to find out how the laws of supply and demand affect market price and availability of products, then I suggest you encourage him or her to start playing one of the more popular collectable card games.
Our son, Robbie, has been playing Yugioh cards for a while now and this evening, while I was tidying up after supper, he hung out with me and treated me to a lecture on economics. Actually, he was going on about how people will not trade the more popular and difficult to obtain cards, which means that they go for really high prices on the internet (I just checked this and discovered Cyber Dragon, which is currently the most popular card, according to Robbie, going for €24,50 on Ebay Germany.)
Wow, maybe this Yugioh thing is not such a waste of time as most parents seem to think. At least it has led to our son having a better understanding of economics than most French university students.