#Psion machines I'll probably never own:

• Psion MC200: Same as the MC400, but with a half-height screen (640x200).
• Psion MC600: One of two DOS machines that Psion made. Laptop form-factor. 15 years ago you couldn't give them away. Now people try to sell them for £700+.
• Psion HC-DOS: The other DOS machine. I've only ever seen it mentioned in the SIBO HDK. Maybe US-only? For all I know, it never actually existed.
• Xemplar Pocket Book III: A rebadged Series 3c. The Pocket Book I and II (rebadged versions of the Series 3 and 3a, respectively) were released under Acorn's own brand and aimed at the education market. The PB3 was released under the Xemplar brand, a collaboration between Acorn and Apple. I don't think many of them were made. I've never seen one for sale, but I do own a copy of the user guide!