JSFiddle - React, Tailwind, and code Playground

HTML

<input id="copies" value="1">
<input id="pages" value="1">
<select id="sizeprice">
  <option value="0.055" selected>A4 ($0.55)</option>
  <option value="0.06">B4 ($0.06)</option>
  <option value="0.07">Letter ($0.07)</option>
  <option value="0.1">Legal ($0.10)</option>
</select>
<button id="showQuote">Quote Me</button>

JavaScript

function getQuote(){
        var copies = parseInt(document.getElementById('copies').value);
        var pages = parseInt(document.getElementById('pages').value);
        var sizePrice = parseFloat(document.getElementById('sizeprice').value);
        var total = sizePrice * copies * pages;
        return '$' + total.toFixed(2);
    }    
    
    
    document.getElementById('showQuote').addEventListener('click', function(){ alert(getQuote()); });