Me and my friends are always obsessive about each others birthday presents.
We usually buy something nice (~100) bucks which comes around to 33 dollars per person. Then we go to Target and buy random stuff like fuzzy pink blankets, jewelry, nail polish, or candy (watermelon sour patches).
Just go on a mini-stuff shopping raid and grab anything that looks cute. I think it's enough to just put a big bag of her favorite candy along with a cute stuffed animal in her FP bag.