Try posting a request in http://www.harp.net/ which is an Irish-based trad harp umbrella website (maintained by Michael Hambly in Co. Mayo – he’s the father of Grainne). You should get some sort of response, and more of the relevent people will probably see your request there. Also trawl through the adverts on the site to find out who’s offering what services. And try the harpmaker Paddy Cafferky, just in case he maintains some stock for hire: Paddy Cafferky (Lisduff, Craughwell, County Galway), or else he may be able to suggest a source. Enjoy your trip!
Patricia, I’m only taking one very small suitcase (basically just a glorified backpack) to Ireland, and part of it is going to be taken up with a sheet set, as I’m staying in self-catering places and hostels, so I don’t really have room for anything extra.
Just thought of this – trying asking Michael Hambly himself (webmaster) if he knows of any harp rentals. At least two of his daughters play harp, and if he’s administering a website like that he’s bound to know a lot of info. He’s also extremely nice (as far as the small experience I’ve had in dealing with him goes) so it’s worth asking. Paddy Cafferky is a lovely man too, and if he has no hire stock be sure and ask him if he can direct you anywhere. He’s lived in the area for decades, and harp people tend to get to know each other pretty quickly. He may be able to point you to some private harpists who have a spare instrument and would like to make a few bob by hiring it out. Worth a shot –