I was pretty lucky to be in a department that was one of the SDSS members. The metal plates they had were only used a few times since each one was unique to the field it was designed for. After they were done with them they sold them to some of us grad students for $20 (the price they would have gotten as scrap). When I move into a house I'm going to mount mine on a wall so I have a little piece if scientific history to look at. :)

One thing to add, too, is that the plates are pretty big! Each one is about three feet across and maybe 1/8 inch thick!