First off you are not a schmuck...you are a dad who took his daughter shopping and wanted to buy her the sweats she wanted.
And while I agree that the signs could have been more explicit they were not but its not false advertising by any means.

And no matter what you or your daughter feel, never ever be afraid to question a price if you think its not right. Teach her to be a savy shopper who asks for what she wants and she will learn to speak up and not let anyone take advantage of her.