People say good things about stoeger, don't have a lot of experience with oe/sxs guns, so i'll let someone who knows more chime in.
If you are considering a repeater, I suggest an ithaca-37. You might be able to pick it up used for 200-300 depending on condition, and it is a bottom ejecting pump. A mossy 500 might work too, though you'd have to deal with the shells flying across your face. Personally, tho, i've used beretta 391s(a righthanded semiauto) , and I never noticed it. You could get a remington 870 lh pump, and it'll be exactly like the 870 but in left hand. The only problem with this is that left hand guns take left hand barrels, which aren't common. (Thats the problem i have with my 11-87 lh, no cheap short barrels) .