(Sorry, I seem to have screwed up editing this post and lost the original text... this is a rough reconstruction. See the movie in a later post.)
I wrote an "Instructable" on how to make a good cheap upgradeable vacuum former using your kitchen oven and a vacuum cleaner:
http://www.instructables.com/id/E8RW98YF3C4XLCQ/
You can also make a high-vacuum system for it, using a converted bike pump, to get finer detail with thick plastic, for about $50, or add a standalone oven for about $30. The high vacuum system can use a converted bike pump or a thrift-store tire inflator, nebulizer pump, or kitchen food sealer. (For volume production, you'd want to have a "real" vacuum pump, but for making a few sturdy cases, high vacuum can be cheap.)
http://www.hackaday.com/2007/07/01/vacuum-bike-pump/
This stuff and more is linked at my new "Vacuum Former Plans" web site, www.VacuumFormerPlans.com