Interactive Graphs is a website from the US which has some interactive graphs. It's not 100% perfect, but it might show at least some of the concepts you want to teach! I think this is probably the most useful page.

For a more simple D-S analysis, I've made this hyperlinked powerpoint, it's very crude but it may well be of use. At some point I'll probably put Consumer and Producer Surplus on, but it definitely won't be for a while.