Bravado  sell band T-shirts from £9.99 GBP . They have TShirts from recent bands like Artctic Monkeys, Killers , Kaiser Chiefs, My Chemical Romance,System of a Down, Trivium. They also sell T-Shirts - from older bands like AC/DC The Clash The Smiths, The Who and The Ramones.
With shops in Ireland asking €40 euro for the same type of thing - even with delivery this works out at about €27 euro for one tshirt. It's hard to find a shop selling decent band t-shirts in many towns in Ireland - so save yourself the hassle and shop online.