Price List

Hi All,
I want to create a price list for purchase order and get discount and bonus items while i am creating a PO
Example:
when i select item XX the system automatic get the price from price list and apply discounts and in some time apply additional discounts plus bonus item

Item code   Price   Discount    Extra discount   Bonus    End of Year Discount    End of Year Bonus
XX              160      10%          25%                  10 EA        20%                                100EA for 10000 EA