One of those is on ebay here:
http://www.ebay.com/itm/221051021938...84.m1423.l2649
I've been "watching" it...but really out of curiosity. Almost $90 opening bid (and shipping), so a little beyond the $50 or so I would pay for it. My VERY first TV I ever owned that i saved up and bought was a Unisonic "briefcase" style 5" combo cassette thing. I do still have that, and it's still going. I've rescued it's vertical at least once since I got it in 1981. I have one that is IDENTICAL to it that is by TMK, and I think TMK (ToyoMenKa) was an actual manufacturer. I pay attention to Unisonic simply because of that first set I still have. I remember playing a CASSETTE of Buckner and Garcia's Pac-Man Fever on that 5" Unisonic when I was like 14 :-)
I also found and bought a JVC 500CX which was the 5" COLOR version of this thing. I got it recently, and SIMPLY because I remember not even HOPING to buy one when I was 14. I felt it was just one of those sets I "had" to find...so I could say I won :-P