THought about in the most eco-sense, biodiesel should drop the price of cooking oil.
The oil should at least pass through one other process first, before becoming fuel...e.g. cooking something.
Virgin oils to fuels (unless they are a byproduct like tallow) isn't the best way IMHO.
The price of energy links to the price of just about everything else, even third world labor, via fertilizer costs to grow their food. Biofuels will make labor prices rise sooner. There's no big inflation yet, since it takes several years for the effects to propagate through the system.
In the area where I live biodiesel has had a lot of publicity and it is always positive. It takes a little effort to collect enought used oil. When you consider the saving and the new people you meet it is worth the time. I enjoyed helping my husband make biodiesel so that was another plus.