GDM-FW900 still worth something?

I have a GDM-FW900, I haven't used it in years since I have no space. It is in good condition, but needs to be calibrated. I have just seen one on Ebay with a current bid of £200 so, is this monitor still worth something and if so will be become more valuable, so should I sell it?

Just sold for £428.

My grandson is still using my old one of these. Where did you sell it for so much ? He could use some cash. If you dont mind me asking.