A few years ago, when I was considering buying a Symphonion, I got the
idea from other collectors that one of these is worth about $1000 less
than a comparable Regina.  That, plus the single comb* and the poor
mechanical and visual condition would place it around $3000 - $3500
maximum in my (admittedly limited) estimation.

 * The really neat Symphonions, IMHO, are the ones with two combs on
opposite sides of the center (not broadside as in the Reginas).  Each
comb has some notes that other one lacks, so the music has an extra
spatial quality (don't say that too fast :-).  Hope this helps --

Mike Knudsen (now in Bath, Maine)