I found an article online that you wrote regarding the value on a commercial invoice titled Repaired Goods: Import and Re-Export. I am a transportation coordinator for my current employer, and there has always been a question in my mind that I'm not sure how to answer.
Many times we ship items to customers free of charge as an incentive for a bulk order or just as samples for them to try out. I've always thought that their actual value must be listed on the commercial invoice whether we charge the customer or not. Usually when I do that, however, I always make a notation on the commercial invoice stating there was no charge to the customer. The value was for customs use only.