I need to build a network of online stores that all have access to the same inventory items (which will contain stock levels, purchase cost to the store, etc.). The individual stores must have access to this centralized inventory and opt to either sell or not sell the inventory items. They should be able to also see the purchase cost of the inventory items, set their own pricing for the inventory items (ability to do this via bulk would be great, like "20% profit for all items in category x"), etc.
Additionally, it is necessary for the individual stores to be able to add their own inventory items to the their stores. Meaning, they are not limited to just selling the items from the centralized inventory.
The inventory would ideally be stored in a single repository so that adds/edits/deletes can be done centrally.
Also, there needs to be a way to categorize the inventory items in a hierarchical manner.
Is there an addon I can use for this? I have never used Expr-esso or Cathrob -- and I'm not sure if those are the only options I should be looking at.