In reply to mloskot:
You can drive to Holyhead then get a ferry to Dublin, it's a three hour drive from there.
Or grab a cheap flight to Belfast International hire a car there and its a 45 minute drive to the crag
Cost will be similar, for short visits 5 days or less I've found fly drive easiest, for longer stays than that taking my car was a better alternative.
Whatever you you choose make sure you do it. Visit fairheadclimbers.com for info on the climbing there.