Hello, I think I've come across this thread a bit too late for my answer to make much of a difference, but I took the exam last year and got a 5, as a level 3 in a non-AP course...actually, the German classes at my school are a complete joke. So self-study is do-able, but in one summer from a German 1 level...meh, probably not so much.
To Pedestrian13, I'd say go the extra mile and do the extra work it might take to pass the exam, because you'll end up having a better grasp of the language in the end, which I think alone makes it worth the time. The recorded voices are generally easy to follow on the exam, since they don't employ all that much slang, and if you look over the MC questions beforehand, you'll be able to get a sense of what they're speaking about and what you need to listen for.
To gauge whether or not you're prepared for the exam, go through the MC questions on the CollegeBoard website, listen to some Angela Merkel speeches on Youtube, and read some articles from maybe Spiegel or Süddeutsche Zeitung or some other reputable German publication (Zeit, FAZ, etc.). I think there are also the writing and audio prompts from the 2012 exam up on the College Board site. If all those go relatively well for you, you should be prepared to take it.
If you want to prepare for it, just keep doing all those things (reading the articles, listening to the speeches, writing practice essays, and so on), since you're not likely to find any prep books for the new exam.