To my way of looking at Model 12s, there are three categories: bangers, shooters and collectors.
Collectors are pretty obvious, for the big bucks they have to be original and almost looking like they are new in the box. The rarer the gun the higher the price it will demand. Should you find an original Model 12 in factory 28-ga, you've struck gold.
Shooters are the nice guns that aren't collector quality. A Model 12 that's had some parts changed and refinished wood and metal isn't a collector's item, but it's still a fine shooter. It's been a while since I was in the market for a Model 12, but the last time I was looking for a shooter, all I could find were bangers, and many of them in 16-ga. Eventually, I found a nice Pigeon grade trap on consignment at my LGS. The owner wanted $1,200 and I made him a 90-day offer of $1,000 -- after 90 days I got a different gun. A few months later, our club's rangemaster picked up the same gun for $850.
The bangers are the guns like one you're looking at and the ones on the floor of BigJimP's LGS. If all you are after is a shooter, get a Browning BPS (or Benelli or Wingmaster). If you have your heart set on a Model 12, find a nice shooter or get the best deal you can on a banger and send it off to
Simmons to be made into a like new shooter to your exact specifications. As my friend, Big Jim, mentioned, hacking a Model 12's barrel for a poly choke conversion is a big negative.