GEO,
Unless you just have to have it, I would limit an offer to $400.00 to $450.00.
The model 12's are getting slightly collectible because they were discontinued, not because they are popular. They are the same size as a S&W model 10, so they are not as concealable as a Cobra or Agent. Also, you will want to avoid using +P ammo and never use +P+. The alloy framed, model 12 is more susceptible to the same problems that soured police departments on using the model 10. Namely frame stretching and being shook loose so that the gun will not work or go out of time.
On the positive side, they are much better to shoot, in my opinion than the COLT revolvers which have smaller grips. I love K-frame revolvers with HOGUE grips. They feel just about perfect in my hand.
I did some side by side testing with a S&W 4 inch model 12 and 4 inch model 15 revolvers. Shooting standard velocity and pressure, 130 grain fmj ammo and 110 grain HORNADY Critical Defense ammo. Both worked well in the model 12 and 15.
I also tried WINCHESTER Defend 130 jhp, which is standard pressure, but it proved unreliable in my guns. This is a problem with most WINCHESTER ammo in my S&W revolvers.
Then I tried some COLT 110 grain jhp ammo made by Double Tap, in both guns, side by side.. This is a higher velocity. It claims to be standard pressure, not +P, but is about a 100 to 150 fps faster than the 110 grain HORNADY load.
The flash is much brighter and the recoil is stronger with the muzzle rising quite a bit more on the model 12, than on the model 15.
It is controllable, but I would save my COLT ammo for use in a heavier gun than the model 12 and stick with the HORNADY ammo. In the model 15, I would go with the COLT load or my ammo of choice for a .38 Special, the FEDERAL HST 130 grain jhp.
I like the model 12 for use as a walking gun. I like long walks after dinner and a 2 inch barreled, model 12 was preferable to my S&W model 36 (about the same weight as the model 12) or CHARTER ARMS Undercover. I could carry the 5 shot model 36 and Undercover in a pocket holster, but preferred the model 12 in a pancake holster, along with an HKS speedloader for reload.
If they won't deal, then try GUN BROKER or another on-line sight.
Overall, they model 12's are good guns, but not as capable or versatile as a steel framed model 10 or model 15.
Jim