Skidcars are awesome training tools. You can induce car behavior that would otherwise take 5x the speed and lot space to pull off, yet the inputs required of the driver to fix the skid are exactly the same as real-world, real-speed. So you can train for oversteer, understeer, hydroplaning, etc, and transfer the skills you learn at 15 -20 mph directly to situations where you're doing 75 or more.
I looked into buying one for a driving school I was considering starting a couple years ago, but they're over $50,000 new not including the car. And they go through a **** ton of tires and seem to require constant maintenance. But they are really cool. If you ever get the chance to experience one, do it.
2009 G8 GT
Road course and racing school junkie, high-performance car control instructor, 9500 miles on 17 tracks and counting