I always made my own, then I hunted with Larrycopper, he had riggem right jerk string and I was amazed how much better it was than my DIY rig. The bungie cord is key, I think it is the same bungie cord you can get at camping store, it's the bungie cord used for those tent poles. Also the "line" itself is high quality, does not tangle and is thin, I have not seen where you can buy that type line.
Here is my jerk cord. You got the mushroom decoy weight, PVC decoy line, bungee cord (you can get this at a camping store, I got it at REI before), my cord is riggem right, but I'm sure you can get this somewhere, probably camping store as well.
With mushroom weight packs away nice..
The weight they give you is overkill, too heavy, and I do not like having to mess with the bag you got to put it in, mainly having to keep it with you when you are using it hunting, it's an unnecessary thing in you blind bag or pocket taking up valuable space and will probably get lost.
I tried a cord I got at academy once, and it got all twisted and tangled, it was the worse.. PVC line will work. And these swivel clips you need, the big ones are hard to find. You want bigger than the clips below..