The various "Snipes", are sleepers on the market. I own a 12 that my Dad bought new, in 1964. I think he paid about $160 for it, and my Mom would still be PO'ed if she found out it cost that much.
I, too, watch what is out there, but, don't really need another O/U (any more guns, really, if I am honest with myself) but a 20 would be a great find.
The firing pin in the lower barrel of my Dad's gun broke along about 1972, or so. Ahlman's had them on the shelf, and we took a trip down to get a pair. I still have the spare my Dad bought. I've always been suspicious of inertia triggers, but, this one has been OK, except for the time it took for the recoil pad to get old and harden up. My Dad had to have recoil pads on all his guns, a notion I still don't agree with.
Our gun has 26" barrels that Dad thought were choked IC/MOD, but, it turns out they are MOD/IMPMOD, and I have had great success with the gun whenever I have dragged it along. I really shoot it better than I should, it has a slight amount of cast off.
I'm saving this one for my Son. I should do something about the white line pad on it, but, I have a few years, until he will need it regularly.
If you use your imagination, you can just make out the "55" of the S55 designation.
I don't have any other guns in 12 gauge with an indicated 17.7 bore. The proofhouse was very clear in bore measurment and chamber length on this gun, they didn't bother with any of that on my Prendelli & Gasperini 20 gauge double.
I'm pretty sure when I feed it the Federal "Pheasants Forever" load of 1 1/4oz of 5s, I'm flirting with using ammunition outside of the level of proof the gun received. But, it is still tight as the day it was made.
A similar 20 gauge would be nice.
Good luck with your new gun.