I don't do much shotgunning, but I've always wanted an O/U. I want to keep it low-end, at least for now. I've been looking (mainly on gunbroker) and I am amazed at how many different brands are out there. I've found a bunch under $500... CZ, Stoeger, Stevens 512, Remington Spartan, Marlin 90, Valmet, Savage 330 and on and on, including some I had never even heard of. I know we have some serious shotgunners here, and I would appreciate your input. What brands offer the best value? Which ones would you stay away from? I would prefer single selective trigger and screw-in choke tubes. Thanks for your help!