http://cgi.ebay.com/USMC-BUCK-M9-Bayonet-Knife-Scabbard-RARE-1-of-175_W0QQitemZ270474432944QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3ef98851b0

what gives???  

Why do people pay thousands for a beat up, worn out, no finish left, WWII or older 1911?
It's a collectible.  Buck made 350 prototypes in three types for the Marines.  The only ones made for the US military that were stamped with the Buck name. All of the others were made under subcontract for Phrobis and had hte Phrobis name.  Some consider it the best of the M9s.  It's a collectors item.  
You could also try looking here,  http://www.google.com/search?client=opera&rls=en&q=buck+m9+bayonet&sourceid=opera&ie=utf-8&oe=utf-8