At one point Mark, previous owner of c5alive, was selling boxed "new old stock" c5's for about £900.
Around the time he sold c5alive he sold one on Ebay for about £600 , so valuing a C5 is not an exact science.
When I placed "Virgin" up for sale I got a few people expressing an interest but no serious offers, so I chose to keep it for exhibitions etc - it was the one used for the studio shots in the recent episode of the Gadget Show.
Fingers crossed Chas gets what he wants, but I'm sure he's aware he is selling in difficult times and quite rightly holding out for the best price.
New "old stock" C5's can only become more rare,so I expect eventually they will go up in price