I think more is made of decoy realism than necessary. There's a fellow that hunts the same marsh as I do. He hunts with his two teen aged boys, and he's a very good waterfowler. He has probably the worst looking set of half dozen or eight decoys you've ever seen. His rig is made up of any odd and end decoy that he's come across in the past twenty or so years. He has a couple of old corkers. A faded Herter's or two and a few other nondescript of hand carved wood, plastic and, I think there was even a paper mache bird in there the last time I looked. There are magnums and standard sizes mixed in haphazardly. His blocks are tossed in a couple of mesh bags without regard. Any paint that remains simple adds to the "speckled effect" on molting birds, to my eye. But, the man knows how to hunt and how to deploy his spread. He kills as many ducks as anyone.
I tend to agree with his philosophy. It's hard to argue with success. When you consider that the bird basically has monocular vision, is flying by at 40 mph and has a brain the size of half a walnut, it's apparent that they just ain't that bright. What they are, is tuned to their environment. In other words, if the spread looks natural, it'll work. And to look natural doesn't necessarily mean that an exact copy of a live bird is needed.
So, if you're on a budget, try some of those "whatever's on sale" blocks and learn how to use them. If you're not on a budget, you can get those super, life like, fully flocked with custom paint job birds. But, you still need to learn how to use them. In my opinion, they aren't going to make one bit of difference to the birds.
I feel slightly sorry for a man who has never patterned his gun, who has no idea how far his chosen load will retain killing penetration. But I'm extremely sorry for the ducks he shoots at beyond the killing range of his gun and load - Bob Brister