Don't know in your area but was www.futureforests.net were recommended before on this site- you can order bare root hedging by post. I ordered loads of lavender to make a lavender hedge earlier this year and found them very helpful. Parcel arrived with perfect plants in the post- what's more there was a 100% survival rate, which is very good.
Coillte, Ballintemple nurseries, Ardattin, Tullow, Co. Carlow. Dont know the phone number but you can look it up. Mainly bare rooted trees and hedgeing. Not so much ornimentals. Very helpful people when I got ash, oak etc 18 months ago.
We got bareroot hedging from Guilfoyles Garden Centre just outside Kildare Town. They were very nice, gave a good discount and even delivered. One year on, the hedge looks great
Check out the Buy and Sell too - you will regularly see ads for well priced bare root hedging at this time of year. This crowd in the UK will also send stuff to Ireland.