The CLK GTR Roadster, $1.9m:
The CLK GTR is a rare beast, and its existence is based almost purely in technicality. Back in the '90s, Mercedes wanted to race in the FIA GT Championship, but, in order to compete, you can't just show up with a one-off rocket ship. You actually have to manufacture a bunch of street legal versions... which means there're only 26 that have ever been made. 25 of them are left-hand drive, with the 26th being custom right-hand drive for the Sultan of Brunei. Yeah. That kind of rare. Allegedly this is the only one left in the US, so when you pull into to the Dunkin Donuts parking lot, the chances you'll see another one are slim.