Hadn’t ever heard of it till now and probably for good reason. It’s more theoretical than real. If you could build it for $100 and produce significant energy then wouldn’t someone be doing it and selling it?
The theory was established in 1974 and the alleged discovery was in 1994 so it’s not like all these scientist didn’t have a $100 to throw down to build an actual unit that sustained itself.
It appears that at least one of the units is a booster not a generator. You can boost the power for a substantial gain but must have input power.
I’d be careful on buying anything from anyone making these claims. I can tell you I’m not smart enough to build anything like this without the real possibility of the fire department being involved.