Customer Discount Matrix:

This module allows you to create a special discount structure for individual customers or types (groups) of customers. You can discount a single product or a group of products (providing they have a common link eg. all from the same vendor) either by a given percentage, or by an amount. This discount can apply  either to a specific price level or all price levels.

Click the image here to see the Customer Discount setup screen that configures who and what receive discounts.