I too bought a meter thingy. One of these....
At first I hated the thing and was glad I only wasted $10 on it. However, the longer I've had it the more useful I've found it.
--The pH function is basically 100% useless. It seems to read about 7 no matter what. Even if it does vary off that figure it doesn't have near the resolution needed.
--I use the light meter function more and more. It actually does an alright job of providing a comparative measure of how much light is being lost in various spots of my cab.
--The moisture function did not seem to work for me at all at first. Seemed like it would always read nearly maxed out "wet". Although I think now that was mostly because when I was checking my soil really
was quite wet (first time grower here). Now that I've learned to let my soil get much dryer, the meter actually provides useful information and uses most of the scale. I only use it to supplement my other methods of gauging when to water. But I'm learning how to correlate the meter's reading with when I know they need water.
Don't know if I'd really recommend it has something worth buying. But like I said, I
do find myself using it every now and again.
$0.02