What's the best thing you've bought for $500? For Art Cairo, of Michigan, that's an easy answer. Back in 1975, he bought this black-on-black Mustang from a newspaper ad that listed it as "special made for Ford family." The ad was asking $525, but he negotiated down to an even five bills. At the time, neither he nor the seller knew exactly how special this Mustang would turn out to be. Read on as we take a closer look at Henry Ford II's personal Mustang prototype.