There are not many free options when it comes to building an e Shop. Of course you have WooCommerce with WordPress. But when you are planning a professional e store, Woocommerce might fall short in many areas.
Luckily, there are software like PrestaShop which make things easier for you. PrestaShop is free, open source, support payment modes like PayPal, Stripe etc, allows selling in different countries based on different currencies and lot more when you try it.