The Abeka high school program can be approached in several different ways. If you choose Abeka (although I don't recommend it), you can join their academy or just get their books and teacher manuals on your own.
There are two options for Abeka high school when it comes to accreditation. If you enroll your child in the Abeka academy, they will get an accredited diploma and Abeka will keep all grades and provide a transcript. You will have to pay quite a bit for this service, but it IS available.
The other option is to choose independent study. You can either purchase the books through Abeka or get them at a discount from ebay or amazon if you like. You purchase the textbooks, workbooks, and teachers manuals if you need them and then your child just works through them throughout the year.
One thing to keep in mind with workbooks is that just because your student completed a workbook doesn't mean that they know the material or understood what they read. Another thing to keep in mind with Abeka is the cost. If you have a limited homeschool budget, make sure you don't go into debt paying for curriculum. If you have been called to homeschool, know that you were not called to homeschool just to go into debt. If there is little money for homeschooling, there are plenty of inexpensive options available that will still give your child a quality education.
Some other options for high school include dual credit where students earn college credit while still in high school. One way homeschoolers can do this without having to be enrolled in a public high school is to use a program like College Plus. College Plus is a mentoring program that shows your child how to earn a college degree in as little as 2 years for less than $15,000!
Sonlight provides a literature approach to learning while Switched on Schoolhouse is a computer driven curriculum. The Well Trained Mind is a wonderful guide for all levels of homeschooling but gives a good curriculum guide for high school students using a classical home school model. These are also good options for high school.
High school students can have a more flexible schedule and I encourage you to help your child get internships and do some job shadowing while they are in high school. Take them on college visits even if they are not planning on going to college and have them take the ACT and/or SAT tests as early and as often as you like.