Add_to_Cart_replacer.js

// ==UserScript==
// @name         Add to Cart Text Replacer
// @namespace    https://holyokecodes.org/
// @version      0.1
// @description  try to take over the world!
// @author       Andrew Pasquale
// @match        */*
// @grant        none
// @require      http://code.jquery.com/jquery-3.2.1.min.js
// ==/UserScript==

(function() {
    'use strict';
    $('div, p, h1, h2, h3, li, span, a').contents().filter(function() {
        // Filter text nodes
        return this.nodeType == 3;
    }).each(function(){
        this.textContent = this.textContent.replace(/Add to [Cc]art/g, 'Buy for Andrew!');
        // Or whatever text you want to replace...
    });
})();