<form action="https://www.paypal.com/cgi-bin/webscr" method="post" target="_top">

  <input type="hidden" name="cmd" value="_s-xclick" />

  <input type="hidden" name="hosted_button_id" value="STKXS9EP7829Q" />

  <table>

    <tr>

      <td>

        <input type="hidden" name="on0" value="Number of Magnets"/>

        Number of Magnets

      </td>

    </tr>

    <tr>

      <td>

        <select name="os0">

          <option value="One">

            One $6.00 USD

          </option>

          <option value="Two">

            Two $12.00 USD

          </option>

          <option value="Three">

            Three $15.00 USD

          </option>

        </select>

      </td>

    </tr>

  </table>

  <input type="hidden" name="currency_code" value="USD" />

  <input type="image" src="https://www.paypalobjects.com/en_US/i/btn/btn_buynow_SM.gif" border="0" name="submit" title="PayPal - The safer, easier way to pay online!" alt="Buy Now" />

</form>