I'm here in Finland, so I used the real deal. It's a small cube of fresh yeast that costs 30 euro-cents, so 0,15 € for what goes in the brew and the wife can make cinnamon buns with the rest :D I'm making most of my runs with this stuff, since it's cheap and the flavour really is unique – very soft and mellow.
I'd imagine a hefeweizen yeast is a good substitute.