You are stocking up for the week at your favorite grocery store. On which of the following items would you expect to see the smallest per-unit price discount?

 
 
 
 
 
 

The third principle of quantity differentiated product lines is that the size of a per unit discount should be lower if the economic or psychological cost of stock outs are high. No one wants to run out of toilet paper, so there are few incentives to offer discounts.