Hmmm...I find that a 12-gauge with 2-3/4" non-magnum shells in 7-1/2 or even 6 shot don't have a whole lot of recoil, particularly not with the 28" vent-rib and full modified(I think...don't recall) choke on my 870 Express Magnum. Now, slap in some 3" magnum deer slugs... Ten years ago I paid $300 new for that with the extra slug barrel (smoothbore). Gunbroker.com is definitely a good place to check.

John, if you go the used route, a semi-auto 12er might be worth a look--the semi-auto action mitigates the recoil somewhat. But it would still be more than a 20-gauge.