They usually don't pay all that much. The most I remember them paying was $6 per drum. A few years later it went to $3. Then, nothing. When I asked where the money was, they said that they should actually be charging, but decided not to. (yeah, right)
I would find out exactly what they are paying for a drum, and then, either match it, or beat it. The end result would still be less than $2.50 a gal.