Lots of multi-port stop loops BCN-BCN over to Italy and back and some including Tunis with most of the major cruise lines: MSC, Costa, Celebrity, Holland America, Disney, Carnival, Royal Caribbean -- easily under $2000 depending on cabin choice and length of cruise. 7 day typical, but some with more stops and distance covered over to Greece etc at 14 days.
Try doing a search on "90 Day Ticker" which can show you who is leaving and returning from BCN, or any other combination you want for the time period you have.