I guess the cheapest way is to obtain an old 'O' level physics textbook for reference. It helped me a great deal when it came to the basics.
These books also seem to have a great way of bringing things back to basics as they're meant for high school. Funny though how it makes more sense reading it when you're an adult and no sense when you're in high school. Different motivational levels I guess.
Also websites for high school students on the subject can offer graphics as good as what the commercially produced (and expensive) CDs would give you. Hope this helps. Good luck
