If you can do it offline, you can do it online too!
Based on your relationship, contract, and the volume of transactions with a corporate customer, you can have different rates for different customers and their products. The Flexi web to print system for corporates allows you to define individual rates for multiple quantities for each customer.
Based on your agreement with your customer, you can also offer the Rate Modification facility to your customer. As an Admin, you can decide if you want your customer to only view the rates or view and modify rates.