maybe...go here: https://contactretail.apple.com/Help to chat with an Apple specialist..... and that:
order a german keyboard in US - Apple Community...maybe if you could find an Apple Store nearest to you, or an Apple products vendor, and give 'em a call, I'm sure they have a phone number of some sort.... as I'm sure you know, Apple doesn't ship internationally, so you'd be asking your family to ship it to you from Germany to Australia... I don't know if you can be in Australia and go to the Mac Store in Germany and order and pay for a MacBook Air...I suppose it's technically possible.... ( dunno exactly how, though) . If you were to get your family to ship it to you (send it over) the cost would be pretty high, I guess, plus you'd have to insure the package. pay for shipping, customs fees and taxes, hopefully keeping the risk of damage or loss sorta low, hopefully.....
as for the special characters, no problem, you'd just have to set the keyboard input to German rather than US or UK English..... there's also some kind of keyboard stickers/top cover you can get which has the special characters on it....wow, Pituophis, you really stumped me on this one....
I'd better go have a cup of coffee, I think my brain's starting to run on empty,
John B