We shot a few over them last weekend
As to cost, please know these are round numbers,
Tyvek, a roll was about $100 and we got 265 decoys out of it with some left over to make flyers
Coroplast for the heads and backbones was $10 for enough to make 300 decoys (scraps from a sign maker)
Steel stake material was $20 for enough for 300 stakes
Paint was fairly cheap
I got "about" 50 cents apiece in them,,,,,,, plus "about" ten dollars apiece of time but who counts that???
I have made two changes from what you see here, 1) I washed the tyvek (cold water, just a few minutes to work the material), it wrinkles it and it looks less shiny and more like a goose and 2) I moved the stake to the nose/head area, it gives more movement with the wind.
Because I had some totes that the decoys will fit into without stakes I made the stake and body separate. I cut some small washers off of some vacuum line from the parts store and slid them down the metal stake as a stop I push the stake into the ground and put the decoy onto it. 30 mph wind moves them great and they stay on the stake. Two of us can set 250 in less than an hour.