User Exit/Enhancement for blocked release PO if Net Price in PO greater than Lowest Price

Dear Expert

Our management has a requirement to block the purchase order that the value of the net price is larger than the lowest price in the info record, for example if the PO is lower or equal with the net price after comparison by the system at the lowest price in purchasing the info recod it would appear the release procedure PO, and if the price used is higher than the lowest the system will block the PO in order not to create release and needed someone to open the PO, is there someone who can help me here?

Thank for the response

Best regards

Bondan S.B