Berlin is prepared for its budget travellers from all over the world and most of the time it won’t be that hard to find a hostel or cheap hotel. However, be aware that especially over summer, it can get crowded and it won’t be a luxury to make a reservation beforehand. Kreuzberg has several good ‘sleep cheap’ options and one of the reasons might be that is is not immediately in the centre, but it sure is pretty close. As goes for most places, a middle classs or first class hotel shouldn’t be that difficult to find.