Hi,
The one place in Ireland where I want to make sure I have a guide is the Boyne Valley, with all the different prehistoric sites and rich history. I contacted http://www.mythicalireland.com/ and talked with a nice fellow who quoted me 200 euros total for the 3 of us for the day (in late June). Does anyone have anything good or bad to say about this company before I send him my money?
We took a tour with BusEiren out of the Dublin bus station. It worked well for us. The driver gave information and answered questions but not a private tour.
Unless you are really set on a private tour, you might want to check out other tour companies first. I don't know about this company, but the price seems awfully high to me. You might check out www.discoverireland.com or other tourism sites to see if you can find other tours of the area to compare prices.
We did the Mary Gibbons tour to Newgrange and the Hill of Tara. It was about 45 euros and well worth it. She is a fount of information about the history of the area. Also, as part of her tour you are guaranteed getting into Newgrange, not just the replica. We found her website and got our reservation in well before going to Ireland. I highly recommend her tour.