I wasn't aware it's particularly fancy, as you can get it even in discount supermarkets here (Germany) - it costs a bit more than the house brand butter but not by much (I think KG is something like €2-something for 250g).
In the USA, it's usually available at 100% markup over domestic commodity butter. Not terribly expensive, honestly, but the most expensive butter available in many supermarkets, and it's only been widely available in the last 3-5 years. And sadly I suspect the US-market Kerrygold is a slightly different formulation/recipe than I remember getting in the UK.
