How to do cumulative substraction using T-Sql 2005

Try this one (previous one has SQL Server 2008 syntax to load sample data):

DECLARE @Products TABLE (ProductID INT, ProductName VARCHAR(200), Price int)
 
INSERT INTO @Products VALUES ( 1, 'A', 1000)
INSERT INTO @Products VALUES (2, 'B',500)
INSERT INTO @Products VALUES (3, 'C', 200)
INSERT INTO @Products VALUES (4, 'E', 300)
 
 select * from  @Products


 ;with mycte1 as (
select ProductID, ProductName, row_number() Over(Order by ProductID)  rn,Price
 
from @Products)
 
, mycte2 AS
(
 SELECT ProductID, ProductName, rn, Price
 FROM mycte1
 WHERE rn = 1
 UNION ALL
 SELECT n.ProductID, n.ProductName, n.rn,  (m.Price - n.Price) as price 
 FROM mycte2 m INNER JOIN mycte1 n
 ON n.rn = m.rn + 1
)
SELECT ProductID, ProductName,Price FROM mycte2
 ORDER BY ProductID
 
--OPTION (MAXRECURSION 0)
;