Originally Posted by der_saeufer

This is the most important question here.

If the samples are of low or no value, it's unlikely to be worth getting a carnet. Even if they cost a lot of money, "no value beyond a sales aid" is a good way to think about it--classic examples of that are a collection of seven left shoes, a shirt with SAMPLE stenciled across the back in black paint, or a plastic cutaway model of an engine. (The technical term is "no commercial value")

Now, if your sample is a fully functional device that you could sell, then you have to deal with it. A carnet virtually guarantees that you'll never get hassled for duty, but it also absolutely guarantees a trip to secondary every time you cross the border so that CBP or CBSA can stamp it.