I've been looking at that too. $100 is fair to your door but easy enough to fab up on your own too if you want to spend the time. There is not much in materials there. Mostly time tracking down the little stuff. And working out the geometry.
I'm sure there are times when more flex will help and times where it might not. We often have the luxury of wheeling in high traction locations where a front locker will pretty much pull you through most anything.
In today's litigation heavy world I'm not a fan of DD with no sway bar/s that is for sure.
Speski OffRoad LTD, Cargo Solutions for Toyota 4x4's http://www.SpeskiOffRoad.com
"80 series, with a fridge"
1976 FJ40, Project with little progress.
2004 Starcraft 10RT