spectrometers are really cheap, yes its the super cheap ones on amazon that work best. Leds are hare to test btw. Lux meters are a good thing to research, and renting a per meter will be your best bet.
Sadly no. I dont have one. Debating a lighting upgrade or Meter purchase.
Ill check out amazo. If you are going the diy route I think I will have a couple extra boards at the end. I had to purchase more then I would need to meet the min order.