Standard cost error while receiving

Hi,

When receiving the Outside operation PO with item as *OP10,I get a hard error if the standard cost is not maintained in P4105.

My query is how can we maintain the standard cost of *OP10 item in advance as it related to the service given by the outside supplier.Also *OP10 item gets created on the fly when running R31410 so in that case it is very difficult to put the standard cost against *OP10 Item because till the time we donot receive the OO Purchase order and get the error the user donot think of putting a standard cost.