Where you start your journey from, and the day of the week, can make for a big difference in cost and availability (also: was that quoted fare one-way, or round trip?).
As far as I know, there are still "issues" with Willi Brandt International, and Tegel is running at over-capacity. It may be cheaper for you to fly into Frankfurt-am-Main (FRA), and take a local in-country flight, or take part of your trip via train (the Friendly and Reliable DB). Alternatively, flying into London-Heathrow and then into Berlin; or into Hannover or Leipzig and then continuing on by train, might work out cheaper.
My last two trips were from Sacramento, California; they involved connections through Phoenix, Arizona, Philadelphia, PA, and then...Munich. I continued on by train in 2013 to Regensburg, and caught a ride with a very friendly local fur (and got the bonus of a walking tour of Regensburg) to Magdeburg. This past year, I flew into Munich and travelled that afternoon via train to Nuremburg, where I spent a couple of days, and then on Tuesday continued on (via DB again) into Sudkreuz station, and then transferred to the S-train for the 4-stop trip to the Sonnenallee station for a one-block walk to the Estrel.
...For some reason, I couldn't get a flight back to the USA from Munich; I had to depart from FRA (How could US Airways fly into Munich, but not out of Munich? I have this mental image of a heap of Aribus aircraft sitting past the Munich runway threshold, used to fly in, and then disposed of)...