i sank a load of money into mini disc, as a music teacher I thought those would be the next great big thing. I had 2 x hi-fi players, a portable recorder, hundreds of "mix" discs of content patiently re-recorded from CDs... ebayed it all last year for a pittance...
I think we still have a commodore Amiga stashed in the attic, with a playstation 1, and an old style nintendo. I kept my sinclair spectrum for years ( finally sold it off ) & I wish I'd kept the BBC micro also - those are pretty rare & valuable now. So long as TVs have scart inputs they can probably still be hooked up.
But I am staying clear of e-reader nostalgia, all is sold except for one Sony 350 which still gets occasional family use.
oh well - time for the next episode of the excellent "halt & catch fire" on netflix