Tear.. that container is the famous Speidel.. I have one as a fermenter. Very thick and sturdy. I doubt I'd want to use it as a cube tho.
Way too expensive. I believe MoreBeer sells one that doesn't have a tap on it.. when available
MadScientist. That unit you are using for your cube looks exactly like the ones I find at the restaurants around here.. They are used for cooking oil. However, the diff, I'd guess, is that mine are very thin.
Firspring.. Glass would be TOOOO subject to exploding by putting very hot wort into them. They are just not made for that. I'd suggest that even the pyrex type, which would be prohibitively expensive, would be suspect. Just too fragile and not designed for this purpose. Also, re Nalgene.. you might want to go to the Wikipedia site and type in Nalgene. Then go down to BPA issues. It ain't necessarily save either. Me... I'm not worried about this issue.. but, that's me.