Weirs in Dublin & Keanes in Cork are similar fashion to UK ADs. Both have pre owned.
Theres another couple around Dublin but prices are way higher (+50%) what you'd see on C24.
Just to be specific here, I visited Dawson Jewelers in Dublin about 2 years ago and they wanted more for a 3 year old IWC Mark Series (no box or papers) than the new ticket price on the same model. Not sure what they were playing at there.