If you come out arrivals, and head left without crossing the road, you will come to the Aircoach desk where you can ask any questions or purchase tickets, You can also purchase the ticket from the driver. there are stops for the Belfast, Lepoardstown, and Donnybrook and Greystones routes. Right down the far end near the terminal building at the front is the Greystones route stop, which goes to the O2.

The Aircoach is the only service from Dublin Airport that would get you to the O2, but for your inital trip in you could get the 747 (Airlink City Bus) into the City Centre, or the 16a (Local Bus with very little space)which you could use prepaid tickets on these vehicles and get the 151 from the CIty Centre to Castleforbes Rd which is very close to the O2 Arena.

The only problem would be coming back would not be possible with Dublin Bus unless your concert finishes pretty early as stated previously as the last Dublin Bus service to serve the Airport leaves the city cente at 22;45. Aircoach operate seperate services from the Dublin Suburbs via the City Centre 24 hours, and the Greystones service I mentioned before goes through the Port Tunnel calling direclty at the O2, but does not serve the City centre.