Strange cost difference at a loggingcamp

[Purifier]

New timber spot spawned and after i saw other AI logging camps making profits with lesser quality i bought the spot and build a logging camp.

To my surprise the cost+freight are much and much higher as at the AI logging camps.

Below is the savegame and 2 pictures, the first showing the cost+freight at an AI logging camp with Quality 84, the 2nd mine with quality 87.
The only difference between the 2 logging camps i see is the place, mine is in the middle of a city the AI's are on the edge of town or outside. But this shouldnt effect the cost+freight (only the landprice).

https://www.dropbox.com/s/wtv2xc58qm92m49/KENN_002.SAV

[David]

I saw a new timber site with a 300%+ price premium in your game. So the high cost of your timber is probably due to price premium of the natural resource site. FYI: http://www.capitalismlab.com/natural-resources.html

[Purifier]

ah yes.. didnt notice that

Will the premium price go down or does it stay premium ?

[David]

The price premium will go down if the total number of sites of that natural resources, including those in production, decreases.

[Purifier]

ah ok

In the meanwhile i tore down the lumberyard, but kept the land so while i wait for other timersites to run out of wood, the price of the land goes up, so if i decide to sell later on, at least ill make some money hahahah