There is no completed SAS that I know of. Spazz started colecting parts. Spazz was planning on using leaf springs. D Struction sold his VX to someone on this board (sorry, can't remember your name) in Alaska and it does not have an SAS...only a suspention/body lift.
WHEN I do mine it will be a linked suspension. Cost will depend on how much of the work you can do. I plan on doing all the prep work on mine but since I don't weld I will leave that up to the pro's (especially since my life could depend on it).