Capture changes to net price

Dear all,

We have a scenario where the net price of an article in a PO can be changed by two transactions. We wish to capture all the changes done to the price of an article in a PO(like the time of change, tcode used, user ID, etc) and i wanted to know if anyone has worked on a situation like this and the process followed for it.

Thanks in advance for your suggestions.

KR,

Devayani