Contract price instead of PIR price on PO

Dear all,

Please help me for my issue:

I have a contract (plant specific) of material with price unit is 4$ per EA

and a Purchasing info record (material/vendor/plant combination) with unit price is 5$ per EA.

My condition type PB00 used standard access sequence 0002.

When I create PO without reference to any purchasing document, I want price in PO using contract price instead of price in info record.

I don't maintain source list for this material.

Please tell me how can I do with so much thanks!