In looking at your available items I would personally be most concerned about the limited editions, mailing multiple items in the same package or items with higher value(Can you replace?). If something does happen to go wrong, either loss or damage or your item were to get inspected(Shipping Intl) you would be following the rules because of declared value. With a secure service you would be covered for replacement/your delivery expenses and so would your customer. Something to consider. On the flip side adding the plastic to the cards "should not" change your declaration of the item. People mail laminated original documents all the time. They are still considered a document/printed matter except with your items they have a suggested actual value. And finally, most important to clearly mark "Do not bend" and make your item as rigid as possible to prevent any damage during transit whichever service you use.
-CM
PS. Giving your customers the option of secure delivery shows them that you are concerned about their item arriving to them safely and as described. They will pay if it the item you have is the one they desperately want.
