The key point in this discussion is that the market is highly illiquid, and that demand far outpaces supply in certain 'hot' areas. Spill-over from that demand has also affected areas not usually though of as being as attractive as the 'hot' areas, if they are within commuting distance.
I am surprised at the rise in prices in areas with much higher tax rates, less favorable transportation links, poorer infrastructure - in the past prices there had stayed pretty flat. But these towns are still within commuting distance to Zürich city, so nowadays folks who have been squeezed out of the hot areas are compromising - and even properties in these areas are trending upwards.
All of which means that what the seller paid for the house X years ago is pretty much irrelevant - he will ask Y, because that is his perception of what the market will bear, what it will take to motivate him to sell.
Knowing what other properties in the neighborhood have sold for
in the last 3-6 months is valuable information as you decide if the property is a fair value
to you.
Of course you can negotiate - but bear in mind that it is for the large part a seller's market if only because of the dearth of properties available. When you start to negotiate down, be prepared to be told, "No. Go away."
Obviously there will be exceptions to this - 'problem' properties are where you have more leeway. But be sure that you can live with the problems.
Given the unique-ness of the CH market, all that really matters is
your perception of price vs. value, and whether or not you can afford the financing for the next 10+ years. Your perception of value may well differ from mine - but in this market defining fundamental value is problematic.
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A word about land prices per m2:
The top price really only refers to currently vacant land that has already been zoned buildable, and usually W2 at that, where access is both possible and laready permitted, and bringing in water, electric, sewer is permitted and not so very difficult.
For instance in my town the average price of land is usually quoted at CHF 3000+ per m2. By that reckoning I should be sitting pretty, eh? But no... My chunk o' dirt with glorious views of the lake and mountains is part of a Quartier with a strict Gestaltungsplan - a new buyer absolutely will not be allowed knock down my quite 'average' house and build a luxury villa. And no one in his right mind (or without serious Vitamin B and the right family name

) would pay luxury villa land prices to end up with an average middle-class house. So my land, nice as it is, is worth less than that eye-popping price per m2.
Most of the land in town has already been built up, so when buying an existing home to estimate the m2 price of the land you need to factor in whether or not you will be allowed to renovate/rebuild a home, and to what standard.
Oh, and by the way - that 3000+ land price really only refers to the few secret plots of (current) farm land that had been optioned off to developers years ago, waiting for a chance to take it out of the BGBB. No individual (unless connected as above) will ever get a chance to buy that land.
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It's a jungle out there, I tells ya.