Firstly, you have to understand that WooCommerce is an open-source plugin for WordPress, so it’s free to install and use its basic package. However, if you want a more advanced online shop and more features for your business, you have to drop some money. Depending on what do you want from your website, you may have to pay from $10 until $300 for one thing.
Secondly, if you want a different theme for your website or a customize design, you may have to pay for each feature. The same story, you have to pay. Otherwise, the price you want to spend on WooCommerce is up to you and your ideas.