We looked into WVO several years back. At the time we were in Western NC You can forget about collecting any WVO in Western NC (anyplace west of Asheville and east of the TN/NC state line). And a sliver (possibly more by now) of North Georgia. A biodiesel out fit was contracting with all the area restaurants. From what I understand, this was becoming a common occurrence.
It used to be that restaurants had to pay to get rid of the stuff, no I believe that most places that produce a lot of it get paid for it.
The restaurants we knew said it was illegal to sell the oil. We're pretty sure $$ is changing hands though it's supposed to be illegal. Every restaurant we spoke to would not give us the oil. It was all committed to the Asheville biodiesel outfit.
I'm pretty sure there is at least one website that provides a map or locations of people who have WVO to sell. You won't be getting it for free, but at least you will be paying a lot less than you would for diesel.
Guess I'm lucky!!! Have been doing WVO for the last 10 years in my VW's & 7.3 Ford. I now have so much of the stuff stored in 55 gal. barrels that I decided to buy my skoolie since I don't need to worry so much about MPG. I will also pull my vw behind it.