Had a look and dates available seem to be..
3rd, 10th or 17th June- Cabin for 4.
Other dates and cabins from £66.
Oh and you dan't have to book the meals but you can buffet breakfast £8. Insurance £9 each but again appears to be optional.
\link{http://www.dfds.co.uk/DSW/EN/Travel/SpecialOffers/2nt_FREE_City_Cruise_Break_to_Stavanger.htm?P36=5HQU6H\Click on the line with the little blue trolley near the bottom.