I am interested in helping you with this task. I can finish the project in the time and budgets specified. I has installed for several companies (manufacturing/commercial/distribution/services) a web enable, light weight and open source PHP/MySql ERP system. It includes invoicing, inventory, receivable, payable, accounting, manufacturing, purchasing and a connection with ecommerce. It handles the order entries as you describes and every user has access to his own data, where they can examine the status of the order, payments done, payable pending, etc. In a kick off meeting, I will supply a action plan to view and check the projects modifications. If you need more info please contact me.