Pawn Shops and gun stores of course. No other ideas for the area I live in (IF You Are Speaking of Colts.)
In the last year I have seen exactly six Colts for sale in my area. Two were NIB DS's that I saw a guy buy both of at the same time...next was an older nickeled DS that I went back to get only to watch a guy walk out with it. Then there was a Python with what looked to be a 8" barrel (?) plus/minus. Then there was a 4"OP .38 sp.
I know of one Colt for sale and it is a used stainless 1911 of some variation. The dealers around my area say basically the same thing regarding used Colts. That is always a variation of "...people don't trade in Colts like they do Smiths...they are more collectible."
In my neck of the woods, they are definitely more scarce.
Nice used Colts are so difficult to find around here so I rely on GunsAmerica more that anything else. It seems that many of the bargains sell within a couple of hours of posting so I presume avid collectors or dealers are scanning the ads on a regular basis. I tend to look for nicer examples that were priced a little too high and then negotiate with the seller after they've been posted a couple of weeks. It all depends on much the seller wants to sell but I've made a couple of good deals that way.
A local pawn shop in Asheville has a pair of older Colt Detective Specials, A very pretty blue 2" and a rough nickle 2". Prices are not so bad but I am not planning to get them.
They had a very ugly 1917 Colt for a long time. It had the smooth grips and lanyard loop, very rough finish and it was bad out of time. Very over priced. I tried to buy it at a better price but the pawn shop had to much in it to let it go. Someone got it eventually. They do show up occasionally.