I own a Stoeger Condor Combo Supreme. It has both the 12 gauge and the 20 gauge barrels. It also has screw in chokes and will take 3" shells. I paid just over $600.00 for it. For the money, you can't beat it. I know it isn't a Binelli, Baretta, Browning or a Ruger, but it shoots pretty sweet for the money. I really like it. Stoeger has O/U's starting at $350.00.
I also have a Berretta 390 that I use for ducks quite a bit. The O/U seems to fit me better though. The 390 LOP is just a tiny bit longer than the Stoeger.
http://www.stoegerindustries.com/firearms/condor.tpl