At email-order-details.php, look for this line:
<th class="td" scope="col" style="text-align:left;"><?php _e( 'Qty', 'woocommerce' ); ?></th>
then add this below it:
<th class="td" scope="col" style="text-align:left;"><?php _e( 'Price', 'woocommerce' ); ?></th>
if somehow the table structure broken, you can fix it by changing the table colspan in email-order-details.php at <tfoot>
Then at email-order-items.php, look for this line:
<td class="td" style="text-align:left; vertical-align:middle; border: 1px solid #eee; font-family: 'Helvetica Neue', Helvetica, Roboto, Arial, sans-serif;"><?php echo apply_filters( 'woocommerce_email_order_item_quantity', $item['qty'], $item ); ?></td>
right below it, you can add this:
<?php
$item_total = $order->get_line_subtotal( $item );
$qty = $item['qty'];
$unit_price = number_format($item_total/$qty, 2, ',', '.' );
?>
<td class="td" style="text-align:left; vertical-align:middle; border: 1px solid #eee; font-family: 'Helvetica Neue', Helvetica, Roboto, Arial, sans-serif;"><?php echo get_woocommerce_currency_symbol() . ' ' . apply_filters( 'woocommerce_email_order_item_quantity', $unit_price . ' each', $item ); ?></td>
The output will be more or less similar to your image link above.
Output
Hope this will help.