Just to be clear and avoid any misunderstanding, Henry says, "At a constant temperature, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid." You might study up a bit on this. And you're absolutely correct, the average American does pay very well just for convenience.But you've got the cathode and anode at the bottom with no membrane barrier so it's not JUST 100% oxygen and hydrogen, it's also ozone and whatever other gaseous byproducts of electrolysis are created when you run electricity through nutrient salts. Ozone is good, since it's more soluble in water than pure o2.
Henry's law states that you cannot increase saturation level above 100% at atmospheric pressure (not even taking temperature into consideration). If you're measuring dissolved o2 in the water right above your overpriced equipment then you're doing it wrong.
I can get the electrodes you are selling from china, and they're much larger and way cheaper for what you get. How you think you can get away peddling a switch-mode dc power supply and the cathode anode assembly in molded plastic for as much as you are is beyond me.
I guess it might be convenient for some people?