I´ve seen U2 in London a couple of times and they were magnificent .. One of the few big bands where the whole group is recognisable .
I´d also like to comment that it´s a good thing you´re selling the tickets at face value .
I had tickets for Jack Johnson ( surfer / guitarist ) from Hawaii .. And sold 2 tickets for a huge profit .. But then later I checked his website and he promotes face value reselling of tickets . ( Great music - laid back ) . I had one more ticket left and sold it at face value to a girl waiting in the queue despite a tout offering me 200 pounds for it .... And I felt good for doing it .
Good luck with selling the tickets I´ll call some friends in Barcelona and see if they are interested .
Steve