really the only way to get one would be to order one from the US store but with a german keyboard... alas the only way you could do this is if you were visiting relatives or someone that would be willing to order it ahead of time and have it shipped to their address and then let you pick it up from them when you get in.
Otherwise, no german keyboard for you 🙁 it's special order. THen again you could always call apple and see what they can do about special order parts or if you can buy a top german case and get it swapped out.