I think I know what happened to them. When stations removed it from service, it often was donated to a college or university where they could get a tax deduction. The college often did not have enough expertise to hook it up and the equipment went into storage. After a period of time, the college needed the space and simply chucked it.
Our station quit donating equipment to these institutions after they wanted US to come out and install it. And THEN to maintain it! These institutions were too CHEAP to hire a tech to take care of the equipment.
I was apalled when a PBS engineer came to us and wanted some old monitors. Fact of the matter, their techs were making more than us. They were unionized with the state employees union. And when they retired, they retired at full pay!
I could go on and on...
Here's a DPS unit on Ebay. While I don't have any experience with this model, I can tell you it will probably need caps in the PS The guy also wants $25 for shipping.
https://www.ebay.com/itm/12713899116...Bk9SR9KS1pDxZQ