Great comments. In my opinion, they already are a collector item.
I'd pay $35K (if I had the money) for the right car with low mileage, perfect shape, and a Starmark Warranty.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".