I have a friend who is part of a biodiesel co-op in beautiful Pittsboro, North Carolina, and he's quite pleased with the whole setup. The gas price is set at $3.50/gal and has been for as long as the place has been open. It doesn't go up, it doesn't go down, it costs $3.50 to make and that's what it's sold at; as my buddy says, hippies aren't into price gouging. Obviously the price would be able to drop greatly if it were being created en masse, but that's still pretty decent, especially if gas prices continue to go up - hell, it's just as much as regular diesel in my area. Besides, you get the pleasure of not giving money to oil companies every time you fill up.
I won't be buying a car anytime soon, but if I do I'm going to give a car that runs on diesel a very serious look. The Triangle is blessed with several biodiesel locations, so it's relatively convienent to me, and I don't seriously expect gas prices to go down again, oh, ever.
FnordChan