Mine came with the pointed stakes, but I think you can buy them through Cabela's.
I used pvc pipe in 1/2 inch and 1 inch diameter, cut to about 36 inches in length with an angle cut for the bottom. The place we hunt has a really soft mud bottom so the pvc needs to be longer than you might think. I stuck a piece of wood dowel in the angled end and cut that off on the same angle. That way you won't get water and mud in the pvc. I also cut a notch in the decoy end of the pvc, which keeps the decoy from turning. There is never enough wind in the woods we hunt to move the decoys anyway and it makes it a little harder for the stake to fall out when you pick up the decoy.
They look very realistic when you sink the pvc deep enough that the decoy looks like it's standing in the water.