There really is no average cost of homeschooling — the amount you spend is up to you. If you use the Internet and your local library, you can keep your costs quite low. If you choose to use a packaged curriculum, costs will run from a few hundred dollars to almost $1,000. Teens who set up their own course of study often combine paid independent study classes, some textbooks, and free Internet or library resources.

No, your sister is not too old. There are several teens in my local homeschool group who started in their junior year, and are doing well. For suggestions on getting started, read "How To Homeschool." To learn how other families with teens homeschool their kids, read Cafi Cohen's book, Homeschooling: The Teen Years.