My kids love play food and play money. So every once in a while we pull them out together and play store with our food toys. They really enjoy this. It is such a great way to teach the concept of money and help them learn adding as well.
The last time we played store, the kids cut up strips of paper and we decided how much each thing in the store would cost- we even priced our pots and pans. I gave the kids $100 in play money and told them they had to get everything they needed to make dinner for their family- and they had no dishes or pots and pans, either.
It was a really fun way to see how much they had left after each purchase- and how much they could buy with the money they were given.
They were really careful to try and get all of the things they needed and not spend their money unwisely! I also talked to them a little about how we have to budget our money as well when we buy food- that's why we can't always buy all the things we want...
It was a really great learning activity!