The cost of sales is the sum of all the costs directly related to your products. "Costs of Sales" includes material, labor, and all other allocated overhead. It may be in "$ per unit" or a "% of the sale price" of your product. 

"$ per unit" means that your cost is fixed and never changes. 

"% of the sale price" means that your cost is variable, depending on the sale price of your product.

The Cost of Sales will be recorded in the Income Statement and all suppliers will be paid with the chosen payment terms on each line.