I just recently aquired a wonderful Gold Cup MkIII in 38 mid range. It is a first year production gun and is every bit of 100% unfired condition. It has its original box..all the papers and tool. In todays market what is a gun like this worth?
I have one of these pistols in the condition you describe:
Value? That depends. I've seen these guns offered for ~$1000. I've seen butchered, I mean "modified" guns offered in the $600 - $700 range. A '61/'62 vintage gun in as new condition like you describe would probably be offered for $1000 - $1500. I keep saying "offered" because I don't know what prices buyers are actually paying for these guns.
Colts command a premium but for this type of gun, a S&W 52 is probably sought after more. Obviously a Colt collector will probably go for the Colt anyway. However the market for .38 Spl MR pistols is not that large and so even though it's a beautiful old Colt, it's value, which is what a buyer is willing to pay, may be diminished somewhat compared to say, a similar pistol in .45ACP or .38 Super.