How to add the cost of product for supplier/customer

For customer

1. Add new product (or edit product)
2. Tick on we sell column 
3. Select Customer and fill in the cost amount 
4. Click on Add Customer to add multiple customer for different cost
5. If the customer is not in the list, learn how to add a new customer

For Supplier

1. Add new product (or edit product)
2. Tick on we buy column 
3. Select Supplier and fill in the cost amount 
4. Click on Add Supplier to add multiple supplier for different cost
5. If the supplier is not in the list, learn how to add a new supplier