There is Conemara Airport - which is owned and run by Air Aerann. I didn't use it as I thought it would be difficult to get a hire car from there - but recent research since I returned has confirmed that the hire car company I used would have delivered the car to this airport: you live and learn, I suppose.
Yes I could have checked on parking charges by going to their website but 1) I have never been fleeced like this before in 25 years of flying and 2) I thought I had no alternative so why bother
Deano