I have gone on the usual websites to check for flights betw/ Edinburgh and Killarney, am aghast at the cost and logistics, one choice actually routing through Paris! Any suggestions or lesser known airlines that I can't find on these websites? One lrg suitcase and one backpack pp, so luggage allowance is a consideration.
Just a couple of ideas that might help. First of all, one large piece of luggage and you are right, it can cost big bucks on the small airlines. Perhaps if you flew into Dublin instead of Killarney, Dublin might be a hub for say Ryan Air or Aer Lingus so might be cheaper. Then you could maybe get a bus or train to Killarney but of course that would add on money and time. Also if you post this question on the site that covers Ireland, GB you might get a "local" poster who can tell you your options. Good luck.
Kerry airport is only served from Frankfurt-Hahn (HHN), Dublin, London STN and London LTN as well as Manchester. So you'd have to play with routings through either one of those airports.
You can fly Edinburgh-Luton and Luton-Kerry on Ryanair for under $100 US (combined price for two separate tickets). Check the Ryanair site to see what your big suitcase will cost you. Use the search engine skyscanner.com to see all your route options on budget airlines.