Have him go to Saxon's website and take the placement test. He might need to use the Algebra II book to work into the Calculus book, depending on how well prepared he is.
After a little bit of looking it's price is 75$. You can buy a good calculus book for a lot less at most used book stores , or even a new book for about half of that.
One of our friends' daughters worked through all the Saxon books Algebra 1 & 2, Advanced Math, Calc and Physics. The daughter was the youngest Math Professor at Simpson College in CA. Mom just gave her the books and solutions manuals and let her go.
You might want to ping the homeschool list for more opinions.
My son did it. I recommend you get the cd-rom program to go with it. We had no problems at all, but we had used Saxon Math for years.
Kassie, aren't you a Saxon math lover?
We used Saxon through Alg II, then my son went to the community college starting in 10th grade for his math classes. Finishing Saxon Alg II allowed him to test into College Alg, and from there he went on to take the other maths, including Calculus.
IMHO, if I were going to choose a Calculus program for independent study, I'd use Chalkdust videos with Dana Mosely. Many college use his videos as supplements.
Here's a link to his site:
http://www.chalkdust.com/comp.html
I only used Saxon up to Advanced Mathematics. After that I just needed help understanding things so I took math at the local community college. It depends on how good your son is at learning things on his own.
We used Saxon all the way into Advanced Math. Did not do Calculus.
My wife loves Saxon, and I always felt that they were excellent in the levels that we taught.
Reminded me a little of Kumon Math in the drills.
One rural school south of Dallas taught from Saxon because their students were too far behind the state curve. Caught up in a couple of years.
Homeschoolers were nearly always ahead of the public school system.
I used the Saxon curriculum from Algebra to Algebra II, Advanced Mathematics (Which has a big focus on Trigonometry), and Calculus (which delves into derivatives, differential equations, and integrals that are necessary for upper-level math courses), and Physics (self-explanatory). I found that Saxon Calculus prepared me WONDERFULLY for my freshman college-level Calculus I class I'm taking right now.
As has been said, Saxon stresses repetition on the problem sets; expect to find problems from 30 lessons back in some sets (which I found to be a wonderful addition). Plus, the solution manuals are an important resource, as they go through the problem solving step-by-step.
You won't regret using the Saxon curriculum. It sure helped me out (my little 12-year old brother's using the Algebra book as we speak).
Random fact: The derivative of an object's velocity equals its acceleration. ;)
My daughter used Saxon Calculus in 11th grade and there were a couple places she needed some help but for the most part, she taught herself from the book. She's in college now and taking first semester calc and says she has not learned anything new yet. Another homeschool freeper, whose screenname I don't recall, made the same comment about her/his son.