As was said earlier, the US one is being sold by Amazon themselves. The German one is being sold by a 3rd party seller, not Amazon. It's just being sold through the Amazon site.
3rd party sellers are free to list things for any price they like - including ridiculously high prices. I personally wish Amazon would put a lid on it, partly for situations like this, but also for situations where vendors adjust prices up or down using software to maximize the $$$ they are getting from customers, which affects the price of items already in your cart.
But, Amazon doesn't do that at this time, so sellers can sell stuff for any price they like. As always, nobody is forced to buy