Are the U.S. Dies ever up for sale? My thoughts are that if they did, the coins made with the Die would be counterfeit, even if there are tell-tale signs on coins made from the Dies. They probably crush them unless they give them to the Smithsonian to be stolen.
They have been sold on several occasions, the 1968 S proof dies were sold off in large lots as scrap metal in a GSA sale. Some of them were then resold by the buyers into the collector market. Is you can see from the ones in this post they used a torch to "puddle" the die faces. Most of the ones I have seen were completely defaced but some like the ones here still had design details. The next sale was through the Mint's own site and those were dies used for the 1996 Olympic commemoratives. Those dies had the faces cancelled by grinding a X across the face. On those most of the design is still visible. The next sale came a few years later, also through the mint and mostly state quarter dies, although some other denomination dies were also sold. On those dies a flat plate grinder was used to grind off the entire face of the die. Some counterfeit error coins (such as of-centers) have been made with the 1968 and 1996 dies, but this would not be possible with the last group of dies since there is nothing left on the face. (I have seen one or two state quarter dies that did still have a little bit of the design.)
