50 thb a gram for decent weed is a good price, probably few people inbetween (I wrote decent weed : green crack can be found around 2k thb a kilogram...)
But farmers who sell on Line for around 50 thb a gram sell the same weed for like 2000 thb for 100g
So if you have a few friends, ...
About thc concentration, a test costs like 50k thb I think. But most farmers just advertise what the sellzr of the strain advertises, without testing.