If you are a woman they have ski wear in the back of Pamela Scotts in Dundrum shopping centre - no affilation, just noticed the ski wear when I was using the changing room.
Don't plan to buy locally...the odd time you can get a good deal (at the very end of the season) but most of the resorts charge a small fortune for ski stuff.
Someone told me to get goggles for the kids in Italy, but I got a good deal in TK Maxx for about €12....the exact same goggles in the resort were €45!!
Bear in mind that you can rent helmets locally for very little.