Range calculation between number of days multiplied by price

I want to calculate the following:

01-Jan-2001 31-Jan-2001 1000 (=price)
01-Feb-2001 01-Mar-2001 2000

I have the start date 15-Jan-2001 until 15-Feb-2001

Now it should calculate 15 days * 1000 + 15 days * 2000

For only 2 rows its easy but it should be able to calulate for a whole range depending on start and
end date....

I added an example to explain a little better