I am fortunate to have grabbed a C-11 when I did. It has NEVER been used, and I have never seen one offered for sale ANYWHERE, ANYTIME. It was a demo model from the McGuire AFB BX. It was a visual demo model only. I also purchased on the same date, a visual demo model TFM-35. IT has never been used either. I keep both in my "Magic Closet" in the event my C-1 craps out, or any of the other Carver power amps I use crap out (M-500t, TFM-42, M4.0t). If I told you the prices I paid you would fall over. I bought the C-1 brand new there also, as well as a Receiver "150", TX-11a, and C-2. In 1991 I demonstrated Carver products at that same base exchange. This allowed me to purchase directly from Carver, a pair of Amazing Platinum Mk. IV's, brand new, delivered to my front door by Roadway, for the princely sum of $1,156. Smartest thing I ever did. Dumbest thing I ever did was to GIVE my brother-in-law my C-9.
I will also go on record as saying that the M4.0t, TFM-42, and TFM-45 are electronically exactly the same, differing only in either cosmetics, or type of power level indicators employed.