My boyfriend happens to run a music school. It's Dublin School of Music. (I thought I should declare my association with it, rather than trying to pretend I'm unconnected.)
I can never remember the details of price and all that important information, but they definitely do violin lessons. The number of the main premises is 01-4929998.
Teach violin myself in the Dublin area to children. The price will depend on what level you are at? i got lessons myself up before in the swords area it was fifty euro for 40 mins - 50 mins. Paid by lesson as was easier than paying by term.