php include problem

I’m in the process of modifying an install of wp e-commerce plugin.
One of the customisations is the inclusion of some social media buttons.

I am calling them manually rather than using a plugin for a number of reasons and the method I am using is by using php include to call a php file containing the relevant code for the buttons.

This method work great for my theme files (e.g. single.php) but I also want to add it to a WPEC theme file (which is stored in wp-content/plugins/wp-e-commerce/themes/default). My social button code file is stored in my theme directory so I added this code to the WPEC theme file:

<?php
$path = bloginfo('template_directory') . '/social_buttons.php';
include $path;
?>

But I receive an error:

http://localhost/serge/wp-content/themes/serge
Warning: include(/social_buttons.php) [function.include]: failed to open stream: No such file or directory in C:\xampplite\htdocs\serge\wp-content\plugins\wp-e-commerce\themes\default\single_product.php on line 247

Warning: include() [function.include]: Failed opening ‘/social_buttons.php’ for inclusion (include_path=’.;\xampplite\php\PEAR’) in C:\xampplite\htdocs\serge\wp-content\plugins\wp-e-commerce\themes\default\single_product.php on line 247

Any ideas?

Edit: When I just echo $path it outputs: http://localhost/serge/wp-content/themes/serge/social_buttons.php which is correct. So why doesn’t it include properly?