i hate to continue this thread-jackery, but a couple quick comments
dddiesel said:
How many gallons of fuel do you burn a year? Let's say... 1000.
that's a generous estimation. 40mpg * 1,000 = 40,000 miles in a year. i think that's probably more than most people, even TDI owners, drive in a year. i'm sure there are some, but that's around 110 miles/day or 153 miles/day if you don't count weekends.
Making Biodiesel costs you about $1 per gallon. That's not including setup costs, or your time, just chemicals and electricity.
[edit] perhaps more avid homebrewers can weigh in on this issue, but i know the guy in Omaha who does around 150gallons every 2 weeks says $0.65/gallon including chemicals, electricity and all. his time isn't counted, but if you consider it a hobby rather than a chore then you're just putting your spare time to good use.
If you can weld or have a friend that can, Murphy's plans are excellent. Otherwise, build an appleseed, or use a steel 55 gal drum as a processor.
i don't want to discourage people from using Murph's processors, they're top notch. but for most people the appleseed will be able to do around 40 gallons of fuel in a couple days. if you only run one batch a week that's 2,000 gallons in a year.
disclosure: i do not currently homebrew, i buy ASTM from a local producer. so what i've said is just info i've gathered here and from talking to other homebrewers. hopefully i'll be brewing myself in the spring.