I recently (something like 1 or 2 years ago) bought an used digital piano off of a comrade who didn't use it anymore.
The instrument is perfectly playable, fit for training, and doesn't show much sign of being that much used, so I intend to keep it for a while since it's in working condition. But I expect that I would eventually buy a new one in the (far) future.
Is it on topic to ask what to do with an used old model digital piano? I tried looking around for information about "piano recycling" or "piano trading" or anything, but I couldn't find much for now.