Scalable way to add custom css/js to a page
I had a theme, called bikeswitzerland. There I had a file template.php, where I added the following code:

function bikeswitzerland_preprocess_page($vars)
{
       $nid = array_keys($vars["page"]["content"]["system_main"]["nodes"]);
       $nid = $nid[0];

       $alias = drupal_get_path_alias("node/" . $nid);
       $theme_path = drupal_get_path('theme', 'bikeswitzerland');

       switch($alias)
       {
       case 'ask-us':
              drupal_add_css($theme_path . "/css/ask_us.css");
              break;
       };
}


Use preprocess_page hook in your theme. Upload your css files into a dir and create a table in the database, that stores the mapping between the page aliases/urls and appropriate css files.

Then inside the function check, what is the current page url and attach the appropriate css, like I did. And you'll solve your problem.