Surface plates are weird to buy and sell. I own an 18x24" Starrett Crystal Pink plate in excellent condition. A few years ago I decided to sell it. I advertised it on CL for about a year. I started at $400 and ended at $80. Never a nibble. Then I took it to a meeting of my local metalworking club and tried all day to give it away. No takers. During that time I was regaled with stories of surface plates going bidless at auction.
Then along came Forrest Addy and Richard King. Suddenly surface plates are cool, and prices are astronomical.
Go figger.
And no, I am no longer looking to get rid of mine.
metalmagpie