I'm sorry to be the one saying this, but there is probably a chance that 51st state is indeed dead. Portal has pulled the entire 51st state line of products from their web store (at least at the time of me typing this). It's not out of stock mind you, the products have simply disappeared from the store completely. I can't see this as anything but bad news.
That's interesting. In the German store they still sell the base game and scavengers expansion besides the promo stuff.