You can get a clicker online for just a few dollars, its very light so it shouldn't cost too much in shipping. But your local pet store should carry them, clicker training is pretty popular now and most stores carry them.
Do you have Pets at Home in Ireland - you can get them there. I buy the i-click clicker from Training Lines or Canine concepts on the web. Best if you're ordering something else though as P&P is expensive.