I would appreciate if you could be very careful with the commercial invoice you enclose for international orders.
In Germany, for example, the recipient needs to pay 19% import taxes if the declared value including shipping costs exceeds $30. - Especially during the "50% off" and "free shipping for orders of $50 and more" sale, it can make a huge difference how you declare the goods that get physically shipped abroad.
Example: Somebody orders "Tales of Monkey Island" (including the free DVD), a "Sam & Max" T-Shirt, and the new "Back to the Future" game. - Including the 50% discount on the first two items, that would result in $51.90 and thereby qualify the order for free shipping. (*hooray*)
If you declare $17.48 (50% to "ToMI"), $9.48 (50% of the T-Shirt) and no shipping costs on the commercial invoice for the goods physically shipped, which is actually what the customer has paid for the content of the box, that would be $26.96 overall, so a customer in Germany would not have to pay any taxes at all! - However, if on the commercial invoice...
[*]the 50% discount is not subtracted from the price of the items, or
[*]there are shipping costs mentioned somewhere, or
[*]the costs for "Back to the Future" are also given in the document, or
[*]the free "Puzzle Agent" game is mentioned with a $9.95 value,
... the overall "declared value" would exceed $30, meaning that a German customer would need to pay at least $7.50 import tax; worst case (if the invoice contains all 4 of these "mistakes), this could add up to $20 tax, not to mention that you need to pick-up the goods at the customs office, which might be more than 50 miles away if you life in the country.
Therefore please, please, please think twice about what you declare in the commercial invoice.
On the other hand, when I ordered my "free" DVDs for some older games last year, I also had to drive to the customs office, as you declared their value as $1 each, and the customs officer considered such a low value to be implausible for a computer game... :(