About right...the 12s are going for a bit more. Be aware TKM doesn't want to repair the old radios, definitely not from ebay, if something goes wrong. They dissuade thru the repair cost. I got my 12 from TKM around 2005, just sent it to the shop. They grouched a bit, but because they sold it to me (altho the previous owners) it's going to get fixed.
Many, if not most, of the original techs retired a couple years ago when the new owner took over.
I'd rather get a new radio or GPS but about $500 to repair vs $6-12K is a HUGE motivation for repair.