Sacrifice is a great sunnah on those who can afford to do it; so, if your parents cannot afford to do it, they are excused; it is not obligatory on their daughter to do it on their behalf; however, if she does that would be an excellent deed.

If you are independent, then it is best that you do it on behalf of yourself. If, however, you are dependent on your parents, they can do it on behalf of the whole family. The Prophet's companions used to do one sacrifice on behalf of the entire family.