I nearly always buy my music from the net these days because its so much cheaper than the likes of HMV or Golden Dicks (sic).
Apart from Cdwow and Play everybody should check out www.deepdiscountcd.com, they are based in the States and do charge for delivery to Ireland but with the exchange rate with the dollar been pretty good at the moment it still works out quite reasonable.Expect to wait 10 days for delivery but if you order 4 cds from their very large catalogue you'll make a good saving.