I would love to see what I can do to help you out here, but I just want to clarify what it is that you're looking for exactly. This way I can make sure I give you the best resources that apply to you.
From my understanding you're wanting to have products from different vendors on your store, you'd want to get the money and then you'd want part of that money to go to the vendor. The price would be set up by the vendors and they would let you know the inventory for their products.
For the order itself you want to be able to fulfill and ship out yourself. All aspects of the fullfilment will be done through you.
If that is the case you're ging to want to ge the Multi Vendor Marketplace app. This app will allow you to manage different products from different vendors, it will allow you to split up profits and it will allow you to define how the products will be sent to the customer.
Have you had a chance to take a look at this app? I think it will work perfectly for you.