I'm still a renter but I am tempted to buy, just have to delete my spreadsheet that tells me how much it will actually cost me. For me I do use that seat in the back sometimes and would miss it. And someone has to be the sucker to keep these GA planes flying.
For an approximation, if you look at shares for sale in syndicates that own the types you are looking at. Multiply the monthly by the number of shares, that will be your monthly. Then the hourly rate would be the same provided you fly enough, say 100 or so hours.
I read about permit aircraft on this forum, some of them like Piper Supercubs are most definitely GA in my part of the world; in fact you will most likely pay a premium over the likes of a C152 to fly one. No sure what you have in Ireland.