Not sure that an exact amount has ever been released. There are many prototypes, race cars, movie cars, and others that don't have a defined value. Probably in the hundreds of millions range for total collection.
Some of the cars are irreplaceable so there is no way to figure a price. E.g. the first car called Ferrari. Only 2 left in the world and they have 1. How do you calculate that value. 1 off Rolls Royces. Some would sell for 10s of millions each and they have a lot of cars.
Prototypes. Why would the cost matter? They are valuable period.
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