Yes the prices went up. But I'm able, in general, to avoid peak times. That helps a lot. If MF is 50% more expensive I wouldn't go for that. I think prices for anything holiday related in Ireland has been on the up for years. Eating out or drinking are also very expensive.I thought that Waterford Castle had been bumping their prices up over the last few years (we've actually gone there a few times), but because it ticked a lot of boxes for us, we still went.
I appreciate the point that you are making about what's very expensive, and Waterford Castle is far from cheap - but I seen to recall it being near 50% cheaper than Mount Falcon, with Mount Falcon not convincing me that they were work such a premium.
We stayed in Killarney a few years ago (I try lots of different places). Quality Hotel I think. Truly dreadful, but they have holiday homes (we used the hotel). seem to remember the staff were like slaves and couldn't speak English properly, it was the Celtic Tiger of course. It didn't help that I didn't like Killarney though.
One of my sisters recommended the Lodges at the Mulranny Hotel, on the way into Achill. But she told me a hotel we booked in Morrocco was fab and we thought it dreadful so I'm not sure about her recommendations !