Price and Cost lists in Siebel

Siebel 8.x has 3 different 'lists' that determine price of the product or service. Today I'll talk about cost and price lists.
Cost list is a set of costs for products or services. For example, you buy Nokia 5800 cell phones for 30 euros per one from manufacturer. 30 euros it's the cost of one purchased cell phone for your company.
But you don't sell those 5800 cell phones for 30 euros, isn't it? Because of shop rent, staff salaries and other you must sell those cell phones for higher price. And here comes price list - it is a set of standard prices for products and services. 'Standard' means that you can apply volume discount or another pricing rule for your customer, resulting in price change (discount of markup).
Siebel is a tricky thing, you know.