If you'd like to get into a 500 factory horsepower hot rod without liquidating your 401k, there are a few options. You could get a high mile V10 BMW M5, but if you prefer something that is more grunt and two fewer cylinders, the choice is easy...E63 AMG. Find this 2007 Mercedes-Benz E63 AMG offered for $13,500 in South Elgin, IL via craigslist. Tip from Tyler.
The E63 generation BMW 650i was a monstrously expensive convertible built in the time of monstrous excesses of Teddy Bear Stearns, Lehman Brodudes, and Merrill Lynchmob. The green wave hadn't yet electrified much of the fleet and pedestrian impact standards had only slightly altered the pointy noses of supercars back in 2006 when this next car left the assembly line. In the twelve years since driving off the dealer lot this car has lost more than seventy THOUSAND dollars of value to depreciation (excluding price of options, fees, gas guzzler tax, luxury tax, etc) but still looks like a million bucks to me. Find this 2006 BMW 650i Convertible offered for $8995 in Houston, TX via craigslist. Tip from Jeff.
If you want a fast luxury 2+2 Grand Tourer from the mid 2000s there are a number of good looking cars to choose from -- Mercedes SLK, Jaguar XK8, Aston Martin DB7, Audi A5/S5, et cetera...but if you want something with a manual gearbox and a Bangle-butt, there is only one choice -- the BMW 6-series. Find this 2007 BMW M6 here on eBay bidding for $15,400 reserve-not-met located in Atlanta, GA. 
The CLK63 AMG we posted yesterday was certainly one of the least common AMG built cars to arrive on these shores with numbers in the low triple digits per year -- but this next car was imported in the double digits for the 2007-2009 model years. The CLK63 may have been a unicorn, but the E63 AMG wagon is a real woiperdinger. Find this 2007 Mercedes E63 AMG Estate Wagon here on eBay offered for $25,300 buy-it-now or make-offer located in Tampa, FL.
The e24 generation BMW 6-series went out of production in 1989, and the 6-series badge took a breather for a few years. In 2004, the 6 name was brought back into the spotlight with the release of the Adrian van Hooydonk styled E63 generation. Hooydonk was a disciple of the much maligned Chris Bangle and used Bangle's signature ginormous trunk butt in a way that wasn't quite as detestable as the E65 7-series. Today the E63 generation 6-series is aging quite well and they will certainly be future collector vehicles in a not too distant future, but for now they have been abandoned by their original owners (bankers, lawyers and other members of the 1%) and can be picked up for cheap. Find this 2004 BMW 645Ci E63 here on eBay
, offered for $14,995 buy-it-now or best offer, located in Bronx, NY.