They cost a bit to build mind you, the interior is alpha and omega.
Some examples:
 
 
My cousin's bus back in  07, they won concept of the year - but the bar has been raised insanely since then:
 
 
 
 
Here they're rigging sound equipment In the "main ring" on the Tryvann event:
 
Get the party started 
 
 
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On another note I'm sticking to designing "cover name" logos and other stash for this years buses, not being part of one myself - can't afford it.