Need advice for creating an e-commerce website on a budget

Hello,

I need to build an e-commerce website in a tight time so I will just be using WordPress and woocommerce. However, there is gonna be traffic on the website so using wordpress will be expensive (especially for a country that uses a currency 20x less in value than USD). I am learning to build the backend of ecommerce website so I will take my time to do that (6 months).

I would like to know if after my in house built website is ready, can I migrate from wordpress and not get charged anymore and keep the same domain name so clients still visit the same url but now the payments gateway and everything used is in house.

Any advice please?