The ad doesn’t mention the fact that this is essentially the former security hut at the entrance to a quite large apartment complex. (I lived in a one bed apartment in The Elms around '88/'89. Loved it.)
I think that the price is to do with the potential to build a house on that site that would sell for €1m+ in that location. Or maybe even better two €750k semis side by side if planning is obtained. There have been many new build largish houses built on small sites all around good areas of SCD.