Moving variables from one page to another

you could POST the shop id to the target page. otherwise- cookie, session. or just fetch it on the list page via ajax.

edit – a simple post request via a form:

in your source page:

<form action="b.php" method="post">
    <input type="hidden" name="id" value="42" />
    <input type="submit" />
</form>

in the target page b.php:

<?php 
if( isset($_POST['id']) ):
    echo $_POST['id'];
endif;