I don't want to repeat anything said before, but I was thinking that there must be something she enjoys doing that you could get passes for her and a friend or two, like the movies, one of the museums or parks in the area. If she is babysitting she may be old enough.
Does she like things like taking pictures? You could set her up with a school memory book.
Maybe she would like to treat her family or friends to a lunch or dinner, although that would involve a gift certificate, which was not your preference.
How about a small electronic gadget? Digital photo keychain, bluetooth, something along those lines? They have been on sale for around $25. Most everyone loves those little gadget items.
My last idea is an item of jewelry, such as something sterling silver or a neat, fun type watch. Oh, or maybe cool sunglasses. Hmmm, ok, so that wasn't my last. Maybe a cool school or beach tote bag? Gift are fun!