Abraxas
Explorer
Cold iron is a bad example. It specifically says that a cold iron weapon costs twice what its normal counterpart costs. So the price of a large sized cold iron weapon would be listed price x2 (for large) x2 (for cold iron).The SRD states that a large weapon's price is doubled from the listed price. Does this mean that a large weapon made out of some special material (say, cold iron) only has its listed price in the weapons section doubled, or should the material cost of the cold iron also increase?
As for other special materials - the numbers given either don't follow any pattern for increasing weights or give a flat value per pound. For example an adamantine dagger and an adamantine greatsword both cost 3000gp more than the base item even though the dagger weighs 1 lb and the greatsword weighs 8 lbs - suggesting the fabrication process is the bulk of the cost, not the raw materials. Given this I wouldn't increase the price unless the material gives a price directly related to weight.