I run a small motorcycle shop, so plenty of old fluids lingering here.
As far as collection companies,they run the gamut from informal to charging a disposal fee in my experience in both the MC and auto industry. With fuel prices these days they usually charge a fee if there is less than 500 gallons. Used to be 250.
Personally, I won't pay to have my oil hauled (and with the deuce don't need to now) because I know the services who haul it get paid for it themselves. They usually send it to a refiner who buys it to refine for No3 power plant fuel. At least that is what I have been told by a number of haulers around here, as to what they do with it. They have also gotten very picky about the oil they take. They consider anything other than straight WMO contaminated and charge a hazardous material fee. My WMO had a faint smell of gasoline which most does, and they classified it as hazadrous and contaminated. I just kept it and now I am glad I did.
To answer your question, as most have said, find a farmer or independent heavy equipment service co. They will be more than happy to give you their used oil. Just be sure you have a way to haul it in quantity that won't draw any attention from the local authorities. They're kinda funny about the whole HAZMAT thing.....
with todays way of life and way people are. Check all your P's and Q's