Not all of my products are available in all countries. I would like to display to the user only products that are available in the country that they are in. Can I do this without multiple stores?
Multiple stores gives you the most flexibility. Using our Enterprise Extensions you can manage multiple stores with a single instance of KonaKart and only one database schema.
Each product has 5 custom fields that can be used to filter the products returned. However I don't really see how this could solve your problem unless you duplicate the products in the database and in say the custom1 field, insert the country code for which the product is intended. You would then have to modify the store front application to set the filter every time products are retrieved.