EDIT: Here's how to do it: http://www.rmcybernetics.com/projects/D ... heater.htm
That was just one link from a Bing search - there may be other articles as well. They tell you how to DIY, and they offer the main parts for sale.
Here's their video:
Lots of other youtube videos on the subject. Here's one that uses parts cannibalized from a microwave oven and nothing else:
There may be even better articles and you tube videos:
http://www.youtube.com/results?search_q ... JTq6WhnHKM
HEY BOB - any of your students need a project?