Found this at the local food store, it was $1.99, and says its made of aluminium. The only part that worries me is the plastic thread holding the end together, I think I may boil it in water and see what happens.
Whirlpooling to set a nice cone in the center of the pot seems to work better with a flat bottom BK. In a keggle with the concave bottom it doesn't work for me. It just spreads across the bottom and doesn't cone.