Like 100 or 50 original cost like 200
Maybe. Why would you want to? It may cost more than a new gunas you may have to fabricate some parts. It's best to use firearms as designed rather than reengineer them. you can easily compromise safety.
My Crescent "Empire" cost $200 as a shooter. The serial number is 7787. These are not collectable guns, but mass marketed "shooters". Still works fine!
50-125 or so
The last one I bought was at a gun show and cost me $500.00. It is a 20ga. I have seen a couple that they were asking in the $700.00 range. Most people have never heard of one.
Suggest you contact Browing and get it lettered. Cost is about 40 USD
50-50000 USD depending on specifics
It is possible to fire a shotgun without a choke, but it is highly not reccomended, and they don't cost that much If you select a barrel with no choke (cylinder) it will cause the pattern to be looser than for a barrel of a shotgun that has a tighter choke. The extreme is "full choke" which keeps a tight pattern out to the effective range. Full choke is typically used for waterfowl. A shotgun that is pressed into double duty (shot for small game and slugs for big game) would work well to have modified choke. Slugs have to be designed to fire through a full choke without blowing the barrel but you will certainly shorten the life of the barrel by firing slugs through a choked barrel. If you can afford an extra barrel, then use a cylinder (no choke) for slugs. Remington and other shotgun manufacturers have interchangeable choke tubes (see link) that allow you to screw in the appropriate choke for your quarry.
100 to tens of thousands depending on specifics
If you can find them, they will most likely cost more than the shotgun in worth.
100-300 USD
That would depend on the caliber, and type of bullet, the rifle uses.