It *is* expensive. There were a few on eBay recently selling for $1500 if you're trying to cut down on costs. Also, if you plan on expanding it, you're better off buying a K2600R instead. It is the newer version of it, but has a redesigned board inside. It comes with the KDFX option built in and the piano daughterboard which is required to put in the Contemporary ROM or Orchestral ROM boards. It also has space for 2 additional ROM expansions.
Also, it gets rid of the internal Digitech FX unit which was noisy anyway. The K2600 has a better sound. Also, all of the internal ROM sounds are the same as the K2500.
There's my selling of it (no, I'm not associated with Kurz in any way). I actually don't own one yet but am saving up for a K2600 (or K3000 if it is available by AES in Oct.). One thing to note is that currently, all of these boards have a maximum of 48 notes of polyphony. If this is too little for you, you may want to look elsewhere unless you totally love the sound. With VAST synthesis these machines are powerful. However, I'm not foolish enough to think that they can do it all well.
HTH and good luck with your buy.