Well if your ever interested in trading barrels. I'd be interested. I'm hoping to find someone who wants to trade barrels or is selling a barrel.
Again, you cannot go willy-nilly exchanging barrels, even between the same model gun. Changing them between different makes is usually impossible. (Remington 3200 and Krieghoff 32 are the only exception I know of, since Remington sold Krieghoff the design-but they still need fitting.)
As to what to look for on Simpson Ltd's site when looking at the SxS:
If you want a hunter, not a looker, some of the guns with rough stocks are a good bargain:
Here is a good example of a good solid hunting gun at a good price:
https://simpsonltd.com/sauer-sohn-sxs-with-extractor-z46684/
This one is sold, but it is a good example of what to look for:
This gun was probably owned by a hunting club; It's been taken out and used. It is chambered 2 3/4". (a plus) It is solid mechanically (Simpson's descriptions are very precise-any defect will be mentioned, and are visible in the pics), and there are only three concerns, two are very minor, the other would be major if you plan to shoot it a lot: The small crack about 3/4s up where the lock and wood meet, straight back from the barrel. That is small, I wouldn't even worry until it started getting bigger. The toe of the buttplate is cracked off; this common in such guns. Reproduction ones are made, and originals can sometimes be found at gunshows. Measure the width and height, and bring a tape measure with you.
The other one is the action lever is ever so slightly to the left, which means the locking block is worn. It still has some life in it, if the gun will be used occasionally, (200 rounds a year or less) it's probably good for a decade or two.
It's a good solid Sauer 30 action, (single underlug with a Greener crossbolt pin for extra strength) with an average LOP, (Length Of Pull-from buttplate to front trigger) Full chokes, that has some finish wear where it should be, heck if I were looking for a 12 ga SxS, I'd take the Drive down to Galesburg, Ill. to look at it, if it weren't sold.
I'm sure I'll eventually end up ordering something from them, they have a lot of gun club target revolvers and .22 autos and at decent prices. S&W and Colt, High Standard .22 autos, etc.
Here's one that's again, good mechanically, but she's been rode hard and put away wet:
https://simpsonltd.com/sauer-sohn-sxs-z49203/
Another Sauer 30 action, 14 1/2" LOP, full & full, very little finish left on metal and wood, bores are good, a small gouge on the left side of the pistol grip. The action lever is in about the same place as the other one, again not a big deal, this won't be your Trap gun!
This one isn't pretty, but a good woods gun, you won't need to worry about the finish.
It's still for sale, too.