Here's the famous Milhous theremin in use by a previous owner, Doctor Dread, on his album "Theremin in Dub."
This theremin, as I am sure most of you are aware, was recently listed on eBay for $15,000.00. It closed without any bids; however, the seller noted that the instrument was also being offered privately. So it may have sold outside of eBay.
https://www.youtube.com/watch?v=PHp68CJUTcc&t=0s&list=PLa99UsH96PJzcV7-aBsRzPIxZ0eDEb-TZ&index=1