I missed out on a QY100 with its original box & manual for $200 at my local pawn shop
. But even if I had got it, I'd probably only use it to sequence my Korg Volcas.
One advantage it has, is you can plug in a electric guitar, bass, or mono synth, and jam with it. As far as I know, the QY700 doesn't have that feature! So I might still be on the lookout for this someday.