How to define a Sales customer specific purchasing buy price

Summary

For sales drop ship how can we have a customer specific buy price on the purchase order

Content

Our client is a reseller of goods and services to hospitals, one of their USP is that they are a one stop shop to deliver goods.   

They also take on the negotiation of specific deals between manufactures and the hospitals and then manage the fulfilment of the products from the manufacture to the hospital mainly using Drop Ship functionality.    

A manufacturer works with hospital to develop a new product and bring it to market such as a bandage with silver thread to reduce infections.