title: Set product price in WooCommerce by quantity and weight
body: <p>I don't find how to customize my pricing in my WordPress WebShop with the WooCommerce plugin.</p>
  <p>I would like to have:</p>
  <ul>
  <li>Article A   12€/kg</li>
  <li>Article B    3€/piece</li>
  <li>Article C   12€/colli</li>
  </ul>
  <p>How is this possible please?</p>
  <p>greets
  Wim</p>