The dispensary you are referring to is using GC and mass spec to differentiate themselves from their competitors. There's a news story about it, I'll go hunt it down for you and post a link here.
Essentially, they are offering the improved safety of testing for molds such as
aspergillus and selling certified bud. Gas chromatography and mass spectrometry can identify and quantify the level of each cannabinoid allowing them to post the ratio of CBD, THC, CBN, etc. for their patients. People will finally start to have a way of knowing what they're actually consuming.
I used to pay $1000 per Mass Spec test (not-420 related) so assuming they made 70% GM, their cost was three hundred just to run the test. This would make me think they are buying more than a pound at a time and are certifying on a per lot basis, but I'm speculating.