If you don't want to spend money on 3rd party testing, then I can think of two sure ways to ensure that the input you're buying is worth extracting.
Three if you include the old fashioned Organoleptic Bioassay :)
1) Spend money on in-house testing equipment
2) performing a test extraction
3) Smoke some!
SRI GC sells a $10k unit they claim with give you cannabinoids,
terpenes, and residual solvents (comes in handy later, if you're winterizing). It won't tell you the level of decarb. Might be important. There are work arounds for that.
You'll want to know moisture content as well. Ideally you're already bringing it to a standard value pre-extraction.
Your test extraction would ideally use the same solvent as your production machine. I think OCO labs probably sells the cheapest test sled for your purposes. You might also need their autopilot because matching your production machine parameters is important, and you don't want to sit around all day manually adjusting the decompression valve.
The problem with that strategy is you'll probably want to send most of the test extractions out for 3rd party testing anyway. I imagine some will look good enough, or bad enough that you don't need anyone else to confirm.
The tried and try method is to smoke it. I enter this as "Quality Control: In-house Organoleptic Bioassay" in state mandated records. :)
I would recommend a temperature controlled vaporizer rather than rolling a joint. Using something like the volcano with a single hit sized bag, and a carefully weighed sample allows you to also control the dose from day to day or tester to tester...more than one opinion is probably helpful...and possibly more fun too.
