You definetly want to talk to your Math teachers, especially if there are any decent ones at your school. They generally have easier access to decent textbooks for teaching precalc+calculus, and could probably arrange for you to borrow one.

Beyond that, you can of course buy your textbook. If there is a college campus somewhere near you, I strongly suggest visiting their bookstore and checking out their textbooks. You will probably be able to get a decent deal on a used calculus book (but that's still going to be expensive, like $70).

If textbooks aren't your thing, there are some fairly good online courses available, but that's pretty much something you can find out on your own. (Google anyone?)

You might also be able to get into some community college courses if there is one in your area. (You'll probably be able to learn enough calculus to get yourself started in 2-3 courses) Your guidance counsellors should know something about that. (If not, just go talk to the community college... they tend to know more.)