Hi
There are still a few surviving clubs at the airport.
http://www.dublinflyers.com/
http://www.airportflyingclub.com/
They seem to get plenty of flying done, I live very close to the airport and there Cessnas and Pipers go right over my house.
If you're interested in Weston, it's very expensive. Especially the National Flight Centre. I don't even think they'll rent you an airplane.
The cheapest club at Weston and probably cheapest in Ireland is the Leinster Flying Club,
http://www.airportflyingclub.com/.
They've got a 4 year old Robin HR200, very very nice little aircraft and the price if 80 EUROS an hour. You won't beat that anywhere.
If you're looking for training at Weston look up Adrian from FlightWise, great bunch of guys who are always more interested in training you than fleecing you.
Best of luck,