Interesting price indeed

My guesses are;
It says in the description that there are
40 cd roms with kurzweil native libraries included.
I could not find the details of these cdrom's but the cd-roms for Kurzweil are expensive and can range from $ 95 to $ 1500,-
per piece! So I think this causes the pricetag.
This is not the price for the keyboard itselve.

note:
I payed for my K 2600 S including two extra daughter-rom cards us $ 4.055,-- two years ago.
I mounted a scsi disk myselve coming from an old pc I trashed a couple of years ago.
I mounted 128 mb ram coming from the same old pc.

The difference between K2600 and K2600X are 76 or 88 keys, where I can assure you that the semi-weighted 76 keys have almost the same resistance/action as the 88 full weighted. (which I love and others hate.)
The (s) stands for the built in sampler.