Casio CZ/ VZ/ FZ - Pro Series

Summa wrote:

"It's also known that for instance the 90s SY77/99 synth creates less
alising and sound less agressive then the older Yamaha FM synths..."

Given that, why do you suppose that the SY99 has become something of a fad
collectors' item lately?  I was interested in purchasing one (chose the FS1R
instead), but was surprised to find them going for $900-$1000, and the local
stores told me they never get used ones in.  At one point, I was negotiating
with one guy who probably wanted more than $1,000 for his as he had maxed
out the internal sample RAM, and had all the impossible-to-find cards for
it...

All that for a synth with weaker FM than the norm?

-- Jeremy