I am trying to think of a way to make a cardboard casting of the mold, then fill it with Quickcrete. That oughta get them to weigh at least 350 lbs apeice for under $10. Then, just add a few drivers and there ya have it, a clone at least as heavy for a small fraction of the cost.
In all seriousness, they are not the first to produce a pair of speakers at this price. Time will tell if they are worth buying or not. It would have been interesting to see how the reviewer thought they sounded with DK's own amp in addition to the others tested.
Paul