automatically add character after link

I’m trying to add a >> using » after links using a list_pages function, but every place I try breaks the site.

Am showing the list of children only if there are children. Adding the » after echo children puts the character after the last link, but is not a link itself. I would like the character to be part of each link.

This is what I’m using:

<?php
if($post->post_parent)        /* section navigation */
$children = wp_list_pages("title_li=&child_of=".$post->post_parent."&echo=0"); else
$children = wp_list_pages("title_li=&child_of=".$post->ID."&echo=0");
if ($children) { ?>
<ul class="subnav">
<?php echo $children; ?>
</ul>
<?php } ?>

Thank you!