I have a thing for shotguns. More than half of my collection comprises of them. First two things you have to ask yourself are - new or used, and pump, or auto? I don't know anyone who hunts with double barrels anymore, but plenty who shoot trap with them.
I like older guns, and I still think best bang for your buck is a Winchester Model 12, if you are looking for a pump gun. You can get nice field grade ones for under $300. You will only find them used of course, but there was a reason they made them for decades - they just plain work great! If you are doing ducks and trap, you are going to be looking for a full choke or adjustable choke gun. Be aware that many old adjustable chokes are not compatable with steel shot.
I did buy a Stevens 350 pump brand new last year, and have been pleasantly surprised by this $250 gun. Its swallowed about 500 rounds so far without a single problem. There has been about 50 3" magnum slugs through it also, and its just keeps working. The action was a little rough when I got it, but cleaning the heavy assembly grease out of the gun and shooting it a bunch has made a world of difference. Its a junker gun but works perfectly and I don't care if it gets wet, etc.
I like the weatherby semi auto shotguns if I was buying new. Otherwise I would look for an used Browning Auto 5. Another shotgun made for decades, and for exactly the same reason. It just works...