Bows are a very personal thing,thus you need to take her with you to a few shops and let her shoot a few models and pick the one that shoots best for her...............If you buy her one that doesn't fit her just right or she doesn't enjoy shooting,she probably won't use it much.
Ebay is a good way to save some dough,but how can you try it out before you buy it?????????You can't so your stuck with what you get.