There is a guy in the old cottages on the Cappagh Road in Finglas who will take them. Drive towards the hospital and at the traffic lights look accross to your right. Sorry no phone number!
Don't know if this will really help as you probably want to get rid of them in bulk, but some gardeners would be interested in them to create cold frames and the like - if you know anyone with an allotment they might know some one interested.