Wouldn't sell mine either. A great CD in my opinion is priceless. Although I'd pay top dollar for another 1 just like him. I may be wrong but I say a sure fire, no bs, catch on ear every time type of dog is worth $300-$500. I'd have no problem paying that if it's jam up CD.
I would have to agree with you on your price range for a no nonsense straight up ear everytime type cd. ( I personally have never given near that much for a cd BUT if I was in a bind and the right cd became available I more than likely would )