Complex Pricing

Dear Gurus,

I have the following prcing scenario in Crude oil sale.

Crude oil price change on weekly basis, so user will create record accordingly.

Suppose Condition type PR00 record is as follow.

01.05.2010 to 08.05.2010 PR00 $ 120

09.05.2010 to 16.05.2010 PR00 $ 130

17.05.2010 to 24.05.2010 PR00 $ 150

25.05.2010 to 31.05.2010 PR00 $ 200

Quantity contract is once created for the whole month lets say 01.05.2010 to 31.05.2010 of xyz quantity.

Creating first sales order on 02.05.2010, system call the respective price at order than create deliveryand PGI.

Creating sec. sales order on 12.05.2010, system call the respective price at order than create deliveryand PGI.

Creating third sales order on 20.05.2010, system call the respective price at order than create deliveryand PGI.

Client following POD practice, and wants that price should applicale in the system on which user receive the delivery challan, on that user put DATE stamp and confirm the quantity, same document client use as POD.

Now in POD client input the POD date what is written on Delivery Challan from customer.

Now requirement is this system calculate the price on the basis of POD date, I can do this by input the pricing date at the time of invoicing VF01 pricing date. but there is collective invoice, each delivery suppose to belong different pricing.

Can any guru have any workaround or standard solution.

If have any query please feel free to ask.