I managed to find 3 recently, One I installed about 6 months ago, the guy sold the car and asked if I wanted the TV tuner back, so of course I did. Then I found a D tuner on ebay and bought that, 3rd a guy in the UK was selling a TV tuner that was apparently RNS-E compatible, so I bid and won, I even emailed to guy to confirm it worked before I bid. But when it arrived it was 2002 tuner from a VW, no way it was going to work. The lying bsteward even says he tested it with an RNS-E and titled auction as "Audi TV tuner for RNS-E", I should have known better. So be careful when bidding.
I also found a german Ebay auction showing C tuners as the pictures and if your read the smallest print, they were B tuners which were no good.