[Fantasy] Price of Commodities

[Phantasm]

In building my own fantasy world, I came to the realization that there are commodities in the world which do not have a price listed in either the Basic Set or in Fantasy (I don't have Banestorm, so I don't know if they're listed there). Can anyone give me a rough estimate, in GURPS $, how much some of this stuff would cost?

Commodities:
1 lb wheat
1 lb barley
1 lb rye
1 lb rice
1 lb potatoes
1 lb flour
1 lb linen
1 lb cotton
1 lb iron
1 lb copper
1 lb tin
1 lb bronze
1 lb brass
1 lb steel
1 lb coal
1 lb wool
cow
goat
pig
sheep
1 acre farmland
1 cord wood

Thanks in advance.