Here is a one-off Ferrari Enzo prototype up for sale on the Modena Motorsport website.
According to the description on the listing, this is the only working prototype of the Enzo Ferrari ever to have left the Ferrari factory. It features a V12 powerplant with 680 PS (500 kW / 670 bhp), 30 PS more than the production Enzo, very similar to Ferrari's 1991 Formula One engine.
The car, a 2000 model, was bought directly from the Ferrari plant in Italy. It comes with factory certification from Ferrari (pictured here) to authenticate it.
More pictures available at the source.
An asking price isn't mentioned but, as this is a true collector's item, it can be expected to be...a lot.