There are a few places in Dublin to get affordable wallpaper that doesn't look like it belongs in your granny's sitting room. You can pick up rolls at Dunnes for about 20 quid each, but they only offer about 5 or 6 patterns. Habitat also offer rolls at about 40 euro each. Their patterns are a bit more avante garde, but you have more to choose from and the colours are much bolder.
If neither of those options float your boat, you should definitely have a look at Wallpaper From the 70's When they first opened up shop, they had only a few typical 70's geometric patterns that, to be honest, looked fairly dated, but during the past year, they've continued to offer more and more variety. They range from about 20-60 euro per roll, and here are some of my picks:
This is Ambrosia. It's 39.90/roll and would look gorgeous in a small kitchen!
This elegant pattern is called Boreas. It's 33.90, and I'm thinking diningroom...with lots of pretty lucite furniture.
You might recognise this wallpaper. It's been used in a few shops in town in the past year, including the Top Shop just off Grafton street. This would be a great accent wall for a bedroom. It's 48.90/roll.
They also have a few patterns that might be a bit too busy for a whole wall, but they certainly would look nice as framed A4's (8"x12"), like Labama (below). You can purchase A4's in any pattern from their website for only 50 cent each. I'm contemplating getting a few myself.
They have loads more patterns, and shipping costs to Ireland (they're based in Germany) are pretty reasonable.