Sony Mini Disc player. I bought into the idea that mini discs were going to replace cassettes and the only recordable media at home. A very short time later, recordable CD's became cheap and that ended the mini disc.
Best Buy used to have a section of mini disc from artists and that quickly shrank down to one shelf and then disappeared.
I bought a combo deal of the home deck and a portable player and 10 blank mini discs. Worst. Purchase. Ever.
I still have the home deck and discs in a box in my basement and a few years ago I looked online to see if there was a market to sell the used deck and didn't find much.
That was the last time I became an early adopter of new technology!