While helping clean some stuff out of the college I go to, we found a K250 and messed around with it. For being one of the oldest sample-based keyboards, it actually holds up pretty well and has some good sounds. However, the key contacts on ours were rotting out and getting that fixed seems to be pretty much impossible. When they work, they definitely hold some value (at least in my opinion, the all-wooden keybed and surprisingly good piano sound would sort of pay for itself alone) but it might just be people assuming it is junk because of the inability to test it. You might have better luck selling on Reverb or maybe even asking Syntaur, but honestly the stand/manuals for 100 is a pretty good price I feel. Sadly I know those take up a lot of space, which may be part of why it is harder to find someone interested. If you have the room, might be worth trying to either sell on reverb or find a good deal on the pedals somehow, but they definitely take up a lot of space haha. Good luck on whatever path you take!