you never mentioned the shipping costs of a product. Many products have to be shipped to Ireland and the demand - so the amount of items you can sell in Ireland - is in comparison to the UK quite low -> as a consequence the prices went up
Anyway, very funny is Apple. When you buy a MAC in Ireland you pay usually more than in every other country in Europe, but the central storage centre is in Irland So the transport costs can't make the difference.
On the apple store the laptops are the same price in ireland, france, germany and italy. ipods are cheaper in ireland than france. the difference seems to be some extra french levy. the desktop computers are more expensive in ireland.
the sterling/euro difference for ireland/UK on the apple store is reasonable at the moment at 0.85-0.86 or so.