Originally Posted by
Alsatian
To each their own. I would recommend to a beginner to buy a cheap pump shotgun. Pumps are super reliable and considerably cheaper than automatics. You will learn something about the beating that a waterfowl gun gets when hunting waterfowl (you did say you were a beginner, right?), and after this you may more carefully consider whether you want a more expensive, more complicated shotgun in the marsh or in the duck boat.
I agree with the point Alsatian makes, pumps are reliable and duck guns are abused, which makes finding a used one in good condition a little tough, but it sounds like you are fairly serious if you are willing to invest $750 in your first shotgun. Therefore, I would say you should go ahead and select an auto.
I would give serious consideration to the inertia guns that Benelli, Franchi, and Stoeger have to offer. Benelli is a little higher priced (worth the price in my opinion), but the Franchi I-12 and the Stoeger Model 2000 are more within the range you're looking to spend.
The Remington 11-87 is also within your price range and it is a good duck gun, but it is gas. Nothing wrong with gas guns, but you gotta make sure you keep it sparkling clean to avoid jams. You can get away with a little less frequent cleaning with intertia guns.