Berlin is not actually a cruise port, but is served by the ports of Warnemunde and Rostock. Combined, Warnemunde and Rostock serves as the embarkation point for only fifteen sailings per year from MSC to Europe.
On average Berlin is somewhat inexpensive compared to other ports. Sailings leaving from Berlin during the peak months of spring and summer are much more expensive than the the low season of fall. Look at the diagram below for the monthly average cost per day (Cruises only depart from Berlin between May and September).