Here are some links that might help you. The guy who wrote these has taught AP econ for many years and put these together for his students. If they help, terrific. If not, ignore. :)
They are animated gifs, so you have to have the ability to view those.
http://www.reffonomics.com/pp1.html (PPC's - animated)
http://www.reffonomics.com/economicsystems.html (economic systems)
Okay - now I'm really going home.