The one and only, original 1967 Shelby GT500 SuperSnake is for sale on eBay. They're asking $3,000,000. Carroll Shelby only built one of these, he did 2 Cobras but only one Mustang. The engine is rated at 520 hp, same as the 427 used in the GT40 LeMans winners. The buyer also gets the website supersnake.org.
Considering that the recent Barrett Jackson auction didn't bring the huge dollars many expected, this would be quite a sale.
Link: GT500 SuperSnake - listing has ended