Various sources would suggest the following:
(1) Apple 1 - Designed firsthand by Steve Wozniak and Steve Jobs. Of the 200 originally made, less than 50 are known to exist.
Estimated value (10k-20k)
(2) Apple Lisa - The predecessor to the Macintosh, Apple's first commercial computer.
Estimated value (2k-10k)
(3) DEC PDP-8 - Defined the mini-computer class for businesses. Lasted through the 70's with eight iterations. Less than 10 known to exist. 1965 cost = $18,000
Estimated value (10k-20k)
(4) MITS Altairs 8800 - a DIY kit based on Intels third-generation microprocessor, the 8080.
It signaled to the general public that it was possible for them to own their own computer, and is widely credited with starting the PC revolution. Rumored to have motivated Bill Gates to start Microsoft.
Estimated value (1.5k-3k)
(5) IMSAI 8080 - Immortalized in the movie "War Games". Was first released in 1975, and over the next 11 years IMSAI produced between 17,000 and 20,000 units.
Estimated value (1.5k+)
(6) Xerox Alto - first GUI (considered by some to be the first pc). Was mainly a research computer. Manufacturing run just over 2000 units. Original cost $32,000.
Estimated value (?)
Anyone own any of these?