All the original 998 (or so) Shelby Cobras were aluminum-bodied and were hand-made using such "advanced technology" as the English wheel. However, they were all painted. It is said that no two original Cobras were the same, and they even differed from side to side.
The Kirkham re-creation body is made in Poland in a former Soviet Mig factory, by many of the same workers who used to produce those airplanes, and they use more modern techniques to make them virtually identical. They don't come polished like that, but brushed. It takes an awful lot of effort to get an entire aluminum body to that high state of polish, and I agree, it is rather spectacular.
A Kirkham brushed, AL body and chassis will set you back about $60K, and you supply the rest. They build about 70 a year. Obviously, a one-off would cost a lot more.