A prototype vocoder built for Kraftwerk and pictured on the album Ralf & Florian is up for auction on eBay. Starting bid is $3,800. From the auction description:
The device was used for two studio productions, title “Ananas Symphonie” including synthetic vocals and rhythm track in conjunction with lapsteel guitar and rhythm machine , as well for “Kristallo” with rhythm machine and EMS-Synth.Later used to sound the KW’s intro for “Autobahn…”
It was conceived , built and constructed by electronic engineers in the area of Physikalisch-Technische BundesAnstalt (PTB) Braunschweig, Dipl.Ing P.Leunig and Dipl.Ing. K.Obermayer.
Later the well known german music studio engineering and supplier company R.Barth K.G.,Hamburg, Germany, boiled down the know-how gained from this project into so called MUSICODER which was produced in small quantities.
Link (via Music Thing)