The situation is: the single site wholesale warehouse needs and an online order placing system, order processing facility and stock management. In addition to tag the key requirements are: system for manual registered users, price brackets (simple, percentage based), orders history accessible for users, online payments optional.
In general the idea is to allow a small number of customers (about a 100) to access the stock and place an order, some customers would have a more discount than others. Warehouse manager can process orders and print a delivery letter and invoice as well as control the stock.
What would fit the bill?