I will be visiting Dublin, Killarney, Dingle, and Galway, and would like to spend one night in a real castle. It doesn't have to be in the towns/cities I just mentioned, but can be somewhere along the way or nearby. I know that many of them are ultra expensive. Are there any moderately priced castle hotels that are the real deal? Does anyone have experiences with Blackwater Castle in Cork?

Thanks for your generosity in helping me out with this.

Blackwater Castle is a venue not a Hotel so unless you are a millionaire then a night there might be out.
Most Castle hotels in Ireland are indeed manor houses and some castle hotels are just next to a castle.
You might want to consider Ballyseede near Tralee, Dromoland above Limerick, Ballynahinch Connemara or the US favourites Adare Manor and Ashford at Cong (Galway)

Ashford and Dromoland are both great suggestions, and they are both own by the same people, really friendly and well run. They both have really interesting history too. Either would be a good choice given your destinations so far.

*both owned* that should have said.

Don't know what you mean by ultra-expensive.

In June Ashford has bed and breakfast for 2 in simpler rooms for about $450

Dromoland has a special with dinner bed and breakfast for about 500 euros

I assume this is more than you want to pay - so perhaps you could provide a budget.

Have a look at the options
http://www.irelandyes.com/castles.html

I was going to post the same thing, Tony - Michele has a list of the real castles as opposed to the hotels that are near castles, on her website... www.irelandyes.com