I have no idea of the release
date or the original price but whatever....
The DEX20 offered a variety of FM preset sounds - electric
pianos, vibes, chimes, marimba, etc. - which were selected from
dedicated front panel switches. Some rudimentary effects could be
added and MIDI channels could be assigned to play this mono-timbral
module. But that (as far as I know) was about it.
Given its obscurity, it is obvious that the DEX20 was
not even a minor success for GEM but it has some interesting sounds
nonetheless which might have a place in your music, even today.
I am (as always) grateful to regular Hollow Sun contributor
(and 'the king of obscurity'), Louis van Dompselaar, for this unique