I priced the system for my Chevelle a few years back and I want to say it was in the $5k range. It’s a trick setup, but I don’t think it took off with consumers. I don’t see many rides with the setup.
I have it as well as another friend of mine. I haven't got around to installation of the hydraulic pump so have the suspension static currently. Friend has it hooked up on his and he seems to like it.
I think $5k is about the entry level into the setup ("base" shocks). I got dual adjustable, remote reservoir version.