cost per square metre, one storey extn

Hi,

This is a kind of 'how long is a piece of string' question, but I am just looking for an indication.

I have looked at a house which needs extending. I would not want to submit planning, so would extend by the permitted 40m square- this would just be one room on the ground floor. This would contain a kitchen diner, but I will factor in the cost of the kitchen seperately, it's the bare extn I am looking at.

I am trying to work out if I could afford this, so would like some indication of a cost for this.

The house is in Dublin and like I say, I would be looking at a fairly simple one-roomed extn.

Thanks a million!