Thanks for your answer... And yes I found, finally, how it is possible to limit it to a country. ( you go: General and below general you click on: Pricing and Availability. On Pricing and Availability you go to: All countries or regions selected there you click on "Edit" Then you can select or deselect the countries. I would suggested, it should be also possible to limited the availability to a state or even better to a zip code.

To have a more targeted field of use... Does this answer your question?