Evelrod, you've hit on a big part that a lot of the people who promote widespread homemade bio-diesel always seem to gloss over - how much of their own time is spent making it. I like to make my own beer, and my friends always ask 'how much does it cost'? I tell them that for all of the ingredients to make 2 cases of beer, it can cost anywhere from $15 to $35, depending on the recipe. The real cost, if you take into account the hours I spend cleaning the equipment, brewing the beer, monitoring the fermenting beer, bottling the beer, is a lot more than just the cost of the ingredients. Even figuring conservatively, 6 hours to make a batch at $30/hour turns my $15 cost into $195 for two cases. That's pretty expensive beer!
If it's something you enjoy doing, then you can ignore the time aspect because you're having fun doing it. But if you have to spend an hour or two every night doing something that you really don't enjoy just so you can drive to work the next day, then 'homemade fuel' simply won't catch on enough to make even a small dent in the demand for fossil fuels. It makes more sense for me to work an extra 20 minutes and use that money to pay someone to make fuel for me and sell it to me for a reasonable price instead of spending 2 hours making my own.
Bob