Dunnes Stores actually had some reasonable stuff last year. M&S is good for thermal t-shirts & leggings (Dunnes do them too). Make sure you get the proper thermal stuff as cotton doesn't work, you just sweat, the cotton gets wet and then you get cold!
There's a place in Carrickmines Shopping Centre (I think it's about Junction 15 on the M50) called 53 Degrees North and they have a very good selection of stuff, both cheap and expensive.
By the way, if you know anyone going to Prague in the meantime, ask them to pick you up ski socks. We got really good ones there at great prices.