Mine cost about 3,500 euro but my orthodontist let me pay in installments every 3 months or so when I went to see him to get them tightened. If you were going to get them done in the North you would need to factor in that you may have to take a day off work every 3 months to go to the dentist and get them check and adjusted.
I have braces on upper and lower teeth, total cost 3400 euro, paid in installments. I attend on the southside of Dublin and I find that hassle enough every six weeks to get off work. Would hate to have to take an entire day off to go up north! Especially as it's a two and a half year process for me. I can also claim taxback at the end of each year.