For example, I can spend $10 on the latest and greatest average-sized action figure, and on the same trip I can spend $0.50 on the gumball machine sticky hand toys (or in this case, sticky foot), and without fail, my child will play with the action figure for a total of 2 minutes, and spend the next 4 days playing with the sticky foot until it loses it's stick, pulls apart, and becomes increasingly more and more dirty and disgusting.
Kid-onomics, my friends.