Vendor Wholesale Cost rather then Commission

Hi,



Instead of giving the Vendors commision of the products, we want to pay them the wholesale cost of the product.



e.g. Vendors will have a cost which we need to pay the Vendors when an items sells.



Vendor cost: $10

We sell for $15

Shipping: $5



There we want Vendors payment to be $10. This is not a $ or %, but moreso 2 different prices.



To me, this is much simpler then the commision payout, but I am not sure how to implement?



Any help would be much appreciated