Each extension has its own topic in the «Extensions» category: https://mage2.pro/c/extensions
There is a PayPal payment form at the end of each topic.
If you want to buy multiple extensions at once than you can do it:
- by purchasing a membership (it will give you the access to all the current and future extensions)
- by direct PayPal payment to the
email@example.com email address (in this case please specify the store's URL and extensions you are purchasing in a comment).