You have 2 option for this
one as suggested above my friend
For this type of problem: Activate "Maintain Batch wise Detail" feature by pressing F11. In Item creation set Maintain in Batches to yes and enter batch name as Rs. 50, Rs. 60 etc., and you will be able to store different rates of a single item.
Other Option is ...
DO PURCHASE ENTRY IN PREVIOUS YEAR OF THIS ..
MEANS IF YOU HAVE OPENING STOCK OF RS 50 *3000 QTY AND RS 60*1000 QTY IN 2009-10THEN
DO PURCHASE ENTRY IN 2008-09 OF 50*3000 AND 60*1000
NOW YOU CAN USE THIS STOCK IN CURRENT YEAR
FURTHER IN INVENTORY ITEM
YOU ALSO CAN SELECT METHOD OF METHOD OF COSTING STOCK , THERE IS AVG METHOD OF STOCK IS IN DEFAULT THIS OPTION CAN BE SHOWN
GATEWAY OF TALLY
--INVENTORY - ALTER ---F12 IN THIS --INVENTORY MASTER HEAD--?>ALLOW ADVANCED ENTRY IN MASTER .. YES
SO THAT U CAN CHANGE METHOD OF COSTING STOCK
YOU HAVE TO CHANGE AS FIFO OR LIFE OR WHATEVER OTHERE THAN AVERAGE SO AS TO DIFFERENCIATION OF STOCK ....
FIFO IS SUGGESTED
REGARDS
-KALPESH VEKARIYA - RAJKOT