Hi,
I've not had any direct experience, but my neighbor looked into doing it. He did a very extensive look. His end conclusion was that the sources of veg oil around town were drying up as more people got interested in doing this.

So, I would check to make sure you have a reliable source of raw material.

Gary

Here in central North Carolina restaurant owners say about their grease, "There was a time when we couldn't give this stuff away. Now they're stealing it."