I had a granite patio put in two years ago. I was doing about 25sqm including a couple of steps and setts around the outside, the granite cost €1400 for 30mm thick slabs from a place in Newry which I would recommend (murdockhardwood.com), significantly cheaper than anything I could find down here.
Fitting for mine was somewhere around €2-3k but the builder was onsite doing other work and as part of that had put in the hardcore base for the patio etc. Builder was also from NI and excellent, happy to pass on his details if you want them.
€5-6k seems about right to me too, but will depend on the work required to get ready for the patio to go in of course.