Learn english, save money
I just looked for some books on amazon.de and was a bit surprised. The english versions of the books were cheaper than the german ones. "The Starfish and the Spider" for example was tagged with 16,96€, "Der Seestern und die Spinne" costs 24,90€, the same ist true for "Groovy in Action". Sure, english books (at least paperbacks) are often printed on paper of lower quality and have to be translated into german, but I remember the time when english books in Germany where more expensive than its german counterparts. So, we have a win-win situation, improving our english and saving money.