Who will be responsible for my import duty?

Import duty is what your country customs will charge you when your package passes through your country customs. It's always buyer's responsibilities to clear customs and pay the relevant custom duties. So dear customer, your package import duty will be responsible by importer yourself, we are not responsible for the import duty. Because we have no idea about your importing country's tariff policy and can not confirm the customs cost.
X431.CC doesn't add the import duty in our product price or our shipping cost.