However, if i had the money and very few nieces and nephews and no children of my own I'd buy them for her. For a highschool girl something like this can mean a good deal. To have the cool, latest item would make her feel great, plus spoiled by her favorite aunt. If you have several siblings you could chip in for them.
I spent all of my childhood wearing k-mart jeans and sneakers. I can relate to wanting something just because of what it is. And you are getting quality.
If it is out of your price range, set a price and take her shopping to try on various brands that are a bit less.