I doubt that site uses any of those templates - it looks like it's been properly built from the ground up.
The easiest way to check if a site uses a template/CMS system, as you say, is to view the source code. There will usually be a giveaway clue in the <head>...</head> section, something along the lines of
<meta name="generator" content="Joomla! 1.5 - Open Source Content Management" />