the basic model is




		desirability
	price = ------------
		  volume





in order to prevent infinite results, it's necessary to re-specify it as


		desirability
	price = ------------
		volume + 1




volume is the number of those items already held

desirability may, in rare cases, be negative if you would pay money to get rid of an item




this means that each person has a different price for the item and trading takes place when prices are different.


for example, if one person puts a price of $8 on an item and another $10, it is beneficial for the person

	with the high price to acquire some of the items from the person with the low price by trading 
	
	some of the items for cash or some other asset.