I've heard the same about the white Lowes buckets. On the bottom of the bucket there should be a code that will explain it's use. The bottom of my Ale Pail is HPDE with a 2 in a triangle. Further in the article it talks about not all HPDE 2 is food grade! What? Anyway I just did a quick scan and am going to read the whole thing as soon as I post this.
Also check out bakeries. The frosting they use usually comes in 5 gallon food grade buckets. I doubt they recycle them probably just throw them out. Cheap free bucket maybe.
Attaching a link that explains the other food grade codes.http://www.virtualweberbullet.com/plastics.html