I am surprised that with all of the 100 series out there that no one makes a drop bracket. In my neighborhood it seems like every third house has a 100 series. One family has 3 100 series!
I think the cost would be so high nobody could afford it. Just my thoughts, but generally the 100 series crowd isn't into huge lifts, or overly complicated lift kits. The front end of the 100 is very robust and drop brackets and spacers would make it much weaker. I have jumped mine, slammed down on the bump stops going 50+MPH, crawled with it, everything you can imagine I have done to the front end and I have no issues...
Man...I have spent so much time exploring this and other ideas.......The drop bracket isn't really that hard to make nor that expensive. I also think the higher quality systems out there have been proven on other platforms. But, that always ends in a debate no one wins. The issue that comes into play is the steering gear, knuckle, and anti-sway bar. Here is a thread I started over on Mud that goes into it in more detail about more lift, long travel systems, etc. (yeah, I go by mxndrnks over there...). It was a pretty good discussion I thought between mainly myself, Spresso (Dan) and Autocraft (Darrien).
http://forum.ih8mud.com/100-series-cruisers/520268-diff-drop-questions.html#post6972574
Bottom line is anything is possible with the right amount of cash.... But, you started this to find a low cost way to lift. So, it is all moot anyway.