I've got a couple of those 13 gallon tanks from that same ebay seller as well as a Speidel 30 liter. The 13 gallon ones are pretty nice. I'm using them for grain storage, but they should make fine fermenters.
I prefer the Speidels though, because of the molded threads for the spout on the bottom. It never leaks. Also the wall on the Speidel are somewhat thicker than the ebay tanks.