Pretty girl but she does need help!
At her age she very likely still has many baby teeth in the back. Although for many patients it is easier to just wait until all the permanent teeth erupt before doing orthodontic treatment, there are exceptions and she is one. Just remember that fixing the front teeth will not mean she will not need more treatment later.
As to the cost it really depends on what needs to be done...a simple picture like you sent is really not enough info to give you a good idea. Most orthodontist provide free consultations so just get the ball rolling and make an appointment