Someone on Amazon posted a video saying it was just a battery operated jigsaw with a ball attached to the reciprocating part. If you're interested in trying it, it might save you several hundred dollars.
I added the link too, bec I've been having trouble with photos, but here's something that I made for $5. I rounded the blade with a grinder, but this was just a first attempt that will be replaced with a round steel rod ground flat where it'll fit inside the saw. But the "action" of the device is an intriguing one. I think that it could be of benefit to help trigger points and such.