Vendor Module for Perfex

I have designed full workflow and mock-ups for a vendor module for Perfex. I believe this is a major shortcoming of the software and will be much in demand for current users. Here is a case scenario: I am a designer who buys and manages commercial print services on behalf of my clients. I have designed a brochure and need to get 5,000 printed. ColourPrint Ltd have quoted me £200 to print it I want to add a 25% margin and sell to my client for £250 I want to be able to do this in Perfex when generating proposals/estimates/invoices. I also want to be able to send a Purchase Order [PO] to ColourPrint Ltd, confirming the price (£200), specification and delivery details. The client must not see my PO, purchase price and margin, all they see is the £250 on estimates and invoices. The supplier must never see my selling price. Firstly it needs to work much like clients do at the moment, add a vendor company with associated contacts and all contact details. When a price is supplied I need to be able to add that to projects/estimates etc, specify the % margin to apply. This also has the benefit of logging and tracking which supplier was used for projects. The module needs to be separated as far as possible from the Perfex core files to minimise work and problems when Perfex is upgraded. I see real value in this and would also like to investigate selling this on Envato so a support package of updates will also be required. Can anyone help?