Went to Berlin five years ago and found prices to be much more reasonable than say London or Paris. The city is surprisingly compact and most of the main sights, Brandenburg gate , Reichstag and checkpoint Charlie are easily walkable. My personal highlights were The Naturkunde museum which housed a large collection of dinosaur skeletons including a T Rex and a very moving visit to The Topography of terror which is built on the site of the former SS HQ and documents Nazi persecution in those terrible times. A large section of The Berlin wall is nearby as well. You can do a city tour in a Trabant if the mood takes you.