The Stoeger single trigger coach guns are pretty decent. I have many hundreds of rounds through one in CAS and I did a Form 1 for one of the pair I own and cut it to 12" "because" and it is quite bad ass. Broken down it fits in some very small spaces.
They made one in 20ga and I think they are readily available. I found the single trigger versions to be much easier to run than the double trigger versions.
As the CAS crowd ages out of the game a lot of used ones are starting to come on the market. I suspect that at some point demand will be so low they quit making them.
My only reservation about a 20 is the not so great variety of loadings available. And in reality I find the true low recoil 12ga 8 pellet 00 buck in the 1100 fps velocity range to be similar to standard 20ga buck shot loads in terms of recoil.
It would be a handy and versatile shotgun to have around. Here is one NIB for a comparable price.