The "exotics" are skyrocketing........the standard .38 service revolvers like 10's and 64's have leveled off because there is less demand for them, and there are more out there. Anything with both S&W and .357 S&W Magnum stamped on it is rising slowly. I noticed that the .38 Specials usually get less "respect" on the market. The shorter the barrel, the higher the price.......3" 65's and 13's are a lot higher than they were only a few years ago. You can still get the 8 3/8" 27's for a lot less then the 3.5" models because not many buyers want the "less cool" longer barrels, so I'm told.
I'm no expert but this is what I've noticed. There's no rhyme or reason, people are buying what they want,and paying the asking prices..... or what they think will be worth even more in the future. You gotta decide, if you want something rare, and you can afford it, you might as well get in on it now, or you'll just pay more later.
There's no use trying to figure it out, it just makes your brain hurt. Movies and TV affect buying too. People are paying over $1,000 for used Ruger .454 Alaskans after that Rock movie "Faster" came out, and Ruger has only made "runs" of these guns, and so demand has exceeded supply and sellers are making a decent profit off them. What was a "niche" gun for bear defense has become a "gotta have it" for lots of people who just bought Faster on DVD. Look at what happened to M1 Garand and Carbine prices after the whole WWII interest blew up in the late 90's to pretty much now......all the movies, TV series and games that came out, now you can walk around a gun show and hear 7 year old kids ID'ing M1 Garands, 1911's and at one show I was at, there was an Stg44 with 50 tweeners drooling all over it because it's in all the Call of Duty games.......it's just that now older S&W's have "cool factor" and people want them.