I think that the fly board is a different type of jet pack--different company and even country than the JetLev-Flyer Water Jet --which is the back pack type. The latter costs about $130,000. According to one web site for $6650 US you can buy the model which bolts onto the PWC--and is controlled by the PWC driver. The hand controls, which allow many of those tricks by the person using the jets, is an additional $900. So for a total of somewhere less than $10,000--and A PWC with over 100 hp, you can be up and running! (that would include having a mechanic bolt the thing together etc.
Maybe I am more aware of foolishness vs moderate risk sports; But I can see a lot of people abusing this type of device--Like drinking and running it--doing some "tricks"--and then not coming back up. The other issue, is the force of the water out of the nozzles. Fine if no one is around. But if you see a water blast injury by a PWC nozzle--it is not something that is soon forgotten. There are enough people who abuse the use of PWC's--this opens up a whole new arena of places for abuse of others on or in the water. OK, where do the running lights go? (A few states allow PWC use after dark--if there are running lights!)...