Stoeger has a 20ga SxS that'll go bang when you pull the trigger for well under $1k, but not sure who makes it.

If you're going to look at a SxS or O/U look hard at Browning, Beretta, Ruger, Charles Daly and SKB. There are some very good condition used field guns by these makers.

Avoid guns with barrels shorter than 26". Short barreled shotguns are butt heavy, and "whippy" on the muzzle end, especially the sub-gauges. They mount in a snap, which sounds like a good quality, but they will come off target just as fast.