Is there a possibility to assign a line item in purchase contract to a customer or group of customers

The same material we buy it from the same vendor and 2 different prices:

The first price is 50 Cent per pound and we have the right to sale it to anybody.

The second price is 35 Cent and we have to sale it to a specific customer (1 or group of customer).

Since we work by source list and Purchase requisition and Purchase order.

Is there any possibility in MM by user exit or enhancement to assign the second price to this customer or group of customer in the beginning when we create the contract?