Very well done. I'll try to draft something on volumetric dosing and send it to you for inclusion.
Regarding the current price on the Gemini's, that's just Amazon's wonderful adaptive pricing algorithm. As you note, these should be $30. The price will go back down when demand goes down. In the interim, these (and all of the other brands of this model) do a great job:
https://www.amazon.com/dp/B075Q44TC9/ref=cm_sw_r_cp_apa_i_DAqyFbH2YNZ6Q