The SAM Spotting System costs US$2,995 in the States.
In Europe the same thing could cost you US$4700 (31000kr).
Phillipe Chartrand was selling a similar device called “Flipping Wings“. Seems it’s no longer available.
My old coach, Physical Ed Vincent built his own with bungie and a twist belt. It’s been working for years and years, with constant maintenance.
Click PLAY or watch it on YouTube.
Personally, I don’t need any of those devices to teach twisting. The time lost getting into and out of the belt could be better used.