hmmm it was two years ago now but probably around €21,000 all in. It completely depends on the added extras that you go (Bigger windows, fitted blinds, extra wardrobe space, spot lights, paint, bed, carpet etc.) The actual basic attic conversion was quite cheap I thought and cost around €14,000 plus tax. If you are getting quotes watch out the for the +tax bit, it threw me when I didn't spot it at the start - our fault. We were able to get a home renovation grant at that time too, not sure if it still available but that also takes the money off your tax bill through Revenue.
Something else for you to consider is that your house is going to be turned into a building site. The job takes two weeks from start to finish so if you can get your family (?) out for all of that time, I would recommend it. They will also be doing, as you can imagine, a lot of drilling\sawing\plastering etc. so pick a company that does a clean job and move everything out of their way otherwise you will be doing a lot of cleaning up afterwards. Close all doors and see if they will put down plastic sheeting everywhere. They will also likely store a lot of material out the back (?) of your house - windows, insulation, wood etc.
The only other thing I can think of is if you are ever planning on running network cables do it now and also think about where you want the electrical sockets in the new room to be. Sitting in my attic now writing this and it is the best room in the house.
