I would assume that the chip with the program in it is non-writeable?
Would it be possible to replace it with a re-writeable version?
I don't have a mailstation to lay my hands on, but.....the LCD-LCD driver-case-Keyboard-etc.. alone are worth more than $50. It has an extremely low power requirement and a reasonable footprint too. It should be possible to convert it to a dumb-serial terminal with little more than a single chip replacement--and more importantly code replacement. (PLC based VT-100...there's got to be code around somewhere for that....) Once that is done, all of the programming and processing would be off-loaded to the host PC. Much easier to reconfigure than the vt-100 mailstation.
The uses for such a device coupled to a remote linux PC--or even DOS would be endless:
Data Entry, Point of Sale, MP3 player controls, DVD player controls, X10 (home automation), Data acquisition and display, Digital controlpanels, test equipment display and controls.
Granted the link speed would be <33.6kbps--but for text-only you'd only need 1200bps anyway...
The only limitation would be the phone cord for the thing to talk to the server. It wouldn't be practical to use the thing wireless anyway.