I think it's most stores never have a solid stock of them.If cost is the issue,change the schedule to test less so it lasts longer
how long have you use it for? i heard a lot of people been using it with no problem but its still new on the market. i just bought a 1yr supply to try it out see how it goes.They are doing black friday deal. $13 for 2 months supply, $5 shipping. $18 to try it. They even have a concentration kit. I have had good experience with it. Deals will end within hours.
3-4 months now. I also intermittently test with 3rd party test kit. The readings have been consistenthow long have you use it for? i heard a lot of people been using it with no problem but its still new on the market. i just bought a 1yr supply to try it out see how it goes.