Client setting Order Profit & Loss Calculated Using: <Dropdown> configures what value with be used to determine the item cost on the order:
An email can be generated automatically when an order downloads with an item that does not have the cost set in the client setting. For example, if its set to "Avg Cost" and the item in the order does not have an avg cost an email will be sent out. The email will be sent to the email address on the company settings page and to anyone cc'd on the email template.
Create template and select on Order With No Cost Available email template assignment.