Roland Jupiter-8 Synth, 1983
This metal-clad eight-voice monstrosity was extremely powerful for its time, but it was an unreliable beast, crashing spontaneously, one time in the middle of a gig. I shipped it to Roland in California twice for repairs, but the crashes continued.
I paid $4600 for it back around 1981, I think. I finally gave it away to my teenage next-door neighbor, who grew up to be a professional musician, serving as Mandy Moore's music director for one of her tours.