The $1300.00 range is correct for a new pistol. The Commander is much more expensive than the sandard Government model. You would need to find out what the model you have has in the way of construction differences. I am going by old memeory on this but many had allow frames, the larger safety tang for the web of your hand and all the tolerances were much closer than on regular gov. models. The Skeleton hammer was standard but many of the Commanders were in 9mm and a few were .38 Super.
What you have is a Gov. model that Colt went through and upgraded to make much more reliable and accurate. You got a real keeper there!