I use Bel Ray Food safe grease on my roaster. I got about 1/2 a tube of it when I purchased a year ago, and have about 1/2 of that left. I've been told it's pretty pricey, but it has to be a lot cheaper than new bearings. I try to lube the bearings once every 10 roasts or so. No grease fitting on my machine, I just jam it in the front.
I'll get the part number off the tube when I go out to the shop later today. (as long as I haven't cut that part of the tube away)
-Stubbie