I bought my Harley Benton online, but only because I'm a beginner and didn't want to shell out a lot of money only to decide I didn't like it. If I do decide to upgrade, it will be from a physical shop. Funnily, like @EdwardMarlowe, Matchetts would be my local shop. There's also Bairds and Belfast Music Supplies. I'm sure Edward remembers Session Music, on the Dublin Road. There was also Marcus Music, which became Dawsons, but sadly they have now closed.