Lots of plugins and scripts allow you to implement Pay with a Like, or Pay with a Tweet, but some of them are not flexible and they do not allow for total customization. Small code modifications allow the user to edit everything inside.
For a WordPress site, though, you need dynamic content and you need to be able to display the social payment module just by adding a simple shortcode.
The Social Payments plugin for WordPress allows customization of Facebook page, Google+ page, Twitter text, link and hashtags details. It also uses HTML5 version of all social scripts and very clean source code for theme compatibility.