To my knowledge, Vortxrex is not manufacturing those. I looked into it last year and although he was very helpful in talking to me about how they work and offering ideas on how to make one like it, I don't remember if he was set up to make them. I believe that was his prototype device. I had a similar dry land situation, and purchased a Hydroforce 300 nozzle from Midwest Prospectors. I did a review of it on another list, but the long and short of it was I was very impressed with the performance of the Hydroforce (so impressed that I bought 2 other sized nozzles). The whole dredging rules thing in California - via the intent (and wording) of the law appears to prevent (in an active waterway):
1. Destroying of aquatic habitat for fishes
2. Eliminating the spread of mercury
Using a hydraulic elevator (or hydroforce nozzle) doesn't affect the fish habitat, since it is being conducted outside of the waterway (yet in the dry parts of the streambed) and by the nature of the usage of the nozzle as per the Vortrex video pretty much excludes the collection of mercury. If you carefully read the california regs, they specifically address "instream dredging in active waterways". FWIW.