cw8: As per subject. Not those luxury houses, just the normal apartment ones, flats or single houses that humble working people live in. Just curious and I want to make comparisons.
As others have said: location, location, location.
A small and old single-room flat in the very heart of Helsinki centre costs much more than a big new house on the countryside on some dying area where the local factory or paper mill closed its doors recently.
Unlike with many other "goods", houses and apartments cost exactly the maximum what people are ready to pay for it. After all, basically all apartments are sold in an auction where the highest bidder gets it. The same doesn't really apply to food, computers, games, even cars. Ok, with second-hand they might, on Ebay and such. And the apartment sales are bound by location, ie. you can't sell the cheap house from the countryside to the city-dwellers.