The key is not how you intend to use the land, but rather how it is zoned. (Landwirtschaft/Forst/Bauland, etc.)
Before you worry about cost, you need to determine the zoning, and if Landwirtschaft/Forst/non-residential, determine if you would be allowed to buy it. Then you need to understand restrictions that may apply - as well as the responsibilities that come with the land.
Much of Switzerland's agricultural land falls under the BGBB - which severely restricts a foreigner (even EU and C permit holders) from purchasing. A whole host of rules and regs surround this type of land - a good read (and re-read) of the relevant legislation is recommended.
http://www.admin.ch/ch/d/sr/c211_412_11.html
If the land is under the BGBB, the price is usually set by the canton, at an artificially low price. (One of the reasons for such purchase restrictions.) Land not in the BGBB, but still not zoned as Bauland, will be more expensive.
A good reality-check on land prices would be your bank. Ours has a lot of nifty data by region for all types of properties - they tend to be my first stop for info.
Generally non-residential land (even non-BGBB) is regulated at the cantonal level - you might want to speak with the Landwirtschaftsamt, the Amt für Raumentwicklungt or the cantonal Bauamt if your local Gemeinde is not the governing authority.
If the land is not under the BGBB but still non-residential, you will pay market price. Just be sure that you are not paying building land prices for non-buildable land.
Top give you an idea, I've seen forest land being sold for CHF 6 per qm. I've seen non-BGBB, non-buildable land for sale for CHF 1000+ qm. It all depends on the market.
If it's zoned as Bauland, you pay Bauland prices - no matter what you intend to do with it.
Good luck!
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