Hello Lion-O,
The tcheck looks like a scam.
Once you have shelled out $230 for the spectrometer, you then have to pay $140 a year to use the "breakdown" service so you know exactly what's in what you're testing.
For $700, you can get the My Dx Analyzer and you won't have to keep paying into a subscription to use it. My local dispensary uses this.
There is another sensor but I am not sure if it can or does (app enabled) test for THC or CBD, but it's called SCiO and it's $299 with no subscription fees.
The main app can test for all sorts of things, so it's not a one trick pony like the other meters.
I believe SCiO's sensitivity is like 1%, so theoretically it could test for THC and CBD, but I think you would need to build an app for it to do so.
I hope this was helpful.