There are several sites on the internet that can work together to help you get the best prices on Bob Jones Christian Learning Curriculum.
The BJU Press site gives you the list for each subjects. There are also kits available. For example, a Sophomore distant learner would use this kit.
The site Christian Book Distributors provides info and prices.
Half.com is a good place to start looking for reduced prices. You can search for your book by ISBN here.
Then there are some many other good sites which offer a big variety of homeschool curriculum such as ThisLittlePiggyStaysHome.com and HomeschoolClassifieds.com.