My 7 year old just got a violin for Christmas and I bought it on ebay (cost around 60 euro brand new and came by DHL). I had tried to get a second hand one but couldn’t find one. Try ringing a few music shops as some of them will have second-hand ones. Sound Shop said they don’t do them any more as new ones are so cheap (not my experience). There is a music shop in Drumcondra called Crehans who specialise in violins and other string instruments, so they might be worth a call. Also it is important to have the child measured for the violin, my DD only needed a 1/4 size one (I hadn’t even known they came in different sizes!) Hope this helps.