Quick vent about kids and consumerism

My 8 year old daughter asked if she could purchase a book from the book fair, and I told her I would go with her after school to get it, but I have to get cash first. She was concerned it would be gone and asked if she could bring her own money. When I told her she didn't have enough money for it, she asked if she could bring her money to buy something else - like she might have enough money for a pen or some other gadget or trinket being sold.

I let her take it because it is her money and she saved it herself, but this bothers me. We are so into the idea of buying something that we will bring money to a store (or bookfair) without a concept of what we need or wish to purchase, just for the point of finding something that we might happen to want. In our house, this item will usually end up buried in a corner within 2 days and never seen again.

I think Hannah Montana and The Suite Life are beating me when it comes to consumer education.