In general the closer to the Central Business District is almost always better. However there are other factors aside from raw geographical location that effects price...
> Area safety
> Proximity to local amenities (e.g. those found in Dublin "villages" like Rathmines, Ranalagh, Howth etc.)
> Apartment size
> Development size (100's squeeze together with no focal point or landscaping drags down value... no exclusivity or privacy)
> Local transport links - Luas, Metro route (indeed a solid luas link could easily eliminate part of the value gap based on raw distance to town centre)
> Area appeal - young professionals, mature families... or students and social housing
> Apartment quality & style (architectural points, high quality build vs. shoddy)
> Demand in area for houses (obviously hundreds of apartments flooding an area will drag down prices)
> Age (apartments have somewhat limited lifespans, so newer ones have a premium)
> Misc items such as parking and management fees
> The preception of the area as a renters/investors area or owner occupiers area... people prefer to buy where lots of people settle
> And to an extent unique selling points such as "green development", "sea views", "on-site crech/gym facilities".
However in the end of the day supply and demand in an area will determine price... if lots of people want to live in Blackrock or Ranalagh, then prices will be high, and if only a few people want to live in Phibsboro and Swords, then prices will be lower...