I agree with all the above posts and because I also agree with Ace that there is no absolute answer. Some collector gun models, if you were to find it in mint condition and its rare, that alone would likely be a very desirable and probably expensive gun. Some guns, its just rare and almost any condition, if all original, is very desirable. Others, having the original box and condition is worth quite a bit more than the "shooter grade" or one missing items.
I have my shooters, but I am a bonified collector at heart and have built a collection as such that I am looking mostly for the complete packages in mint condition. But I also know a good deal on the models that I collect, and would buy a lesser item if the price is right. Its just too broad a spectrum to say, such as say.. car collecting.
many of us have many models and Brands as well, not just Colt. My own opinion is that almost any gun not in current production, mint, complete is worth more to somebody that collects them.
The best advice that I read above is to get a book or books on an area if you know what model or models you so desire. These guys and gals know which books to recommend as well. If you want to increase your chances of coming out on top, get photos .. good cell phone photos, anything to post photos and ask questions before you buy. There are alot of fake boxes and labels out there and guns that look good but are refinished and/or have been altered in some way with non original factory or changed grips or parts. That hurts value to a collector, but it may be priced as such too, and still worth it. It's like picking out a spouse. The more blindly you do it and the faster you do it, well .. ya know.
