Berlin is served by the ports of Warnemunde and Rostock, but isn't actually a cruise port. Added up, the port of Warnemunde and Rostock functions as the departure port for only thirty sailings annually from both MSC and Costa to Europe.
Overall Berlin is moderately inexpensive compared to other ports. Cruises scheduled from Berlin during the peak months of spring and summer are much more expensive than the the low season of fall. The chart below shows the monthly average cost per day for cruises from Berlin (cruises only depart from Berlin between May and September).