title: javascript form calculation returns NaN
body: <p>I have an order form and a JavaScript which should calculate grand total from textbox (quantity*price), checkbox and radio, but I'm missing something because i receive a NaN error. Could somebody help me fix it?
  Thanks a lot.</p>
  
  <p><a href="http://jsbin.com/asosos/21/edit" rel="nofollow">DEMO</a></p>