$100

The girls and I were at a bible book store where Megan saw a doll she just fell in love with.  It was a fancy "missionary" doll with beautiful clothes and long hair.  From the time Megan saw it until we left, she didn't stop talking about that doll.  It just captured her attention and she truly wanted to take it home with her.  I didn't see a price tag attached, so as I was checking out I asked the cashier how much the doll was.  She coolly replied, "They're around one hundred dollars."  

So as we're driving off, Megan continues to ask about the doll.  I try explaining that the doll costs a whole lot of money.  I tell her it's $100.  In an effort to get her to understand exactly how much that is we all three counted to 100 fairly slowly.  When we finally said "100", I said, "That's how many dollars it would take to buy that doll.  That's a lot of money."  

Without missing a beat, Megan simply said, "Why don't you just give her a $100 dollar bill instead?"