Thanks, Tom.
I always figured I could talk someone into giving me some, but I never happened to come across any workers when I saw the kind I wanted.
However, on a whim, I stopped into Quality Farm and Fleet and asked if they had any. They did! I got the last roll of it - 50 feet for $20!
I prefer free, but $20 is better than wondering if I might end up in trouble for "liberating" a length of it from a construction site.