Back to the original topic of this thread, for a moment... .
There are a couple of good sources for info on where to buy biodiesel. The first is a database of retailers maintained by the National Biodiesel Board (the industry's trade organization. See:
http://www.biodiesel.org/buyingbiodiesel/retailfuelingsites/default.shtm
The other is a database maintained by the US Dept. of Energy -- its a station locator for a bunch of alternative fuel types: biodiesel, hydrogen, propane, you name it. See:
http://afdcmap.nrel.gov/locator/LocatePane.asp
This one has a cool route-planner tool (helps you construct a route from X to Y across country, going from filling station to station), plus a bunch of nice search tools (example: "show me all the biodiesel stations within 25 miles of zip code 16053").
I'm very enthusiastic about biodiesel. Not only does it make sense geopolitically (get that OPEC needle out of our veins), but a huge amount of research has shown that diesels run cleaner and smoother on biodiesel than on dino fuel, and the stuff has superior lubricity. Bear in mind that Herr Docktor Diesel's first engine ran on peanut oil! 100% biodiesel (called "B100") isn't practical in cold climates... it gels too easily, and conventional anti-gel compounds don't prevent that. However, a blend of up to 20% biodiesel and 80% dino-diesel ("B20") is practical, and still gives you most of the cleaner/smoother benefit.
Unfortunately, REAL biodiesel (i. e. , stuff made from virgin soy or rapeseed oil, to ASTM specs) is more expensive than dino diesel, and probably will be for some time yet (until a barrel of oil hits maybe $70... but be patient, that day's coming Real Soon Now, sigh). There are homebrewers out there making their own 'moonshine' biodiesel from waste vegetable oil (from fryers at hamburger stands, chinese restaurants, or potato chip factories). This stuff can be real cheap (like $0. 70 per gallon) if you don't mind running mystery meat through your CTD

. I personally have a problem with that. This spring I'm going to start burning real B20, just for fun. Hey, if its good enough for Willie, its good enough for me!:
http://www.wnbiodiesel.com
BTW, there's a looooong biodiesel thread here:
https://www.turbodieselregister.com/forums/showthread.php?t=103463&highlight=biodiesel