I bought some GDP from a dispensary a few months ago. It was ok, nothing to write home about. I just clipped a bud off of my GDP, that I'll chop soon, and Damn! I'm in love! And got unexpectedly good pain relief too! I'll sample disp. weed occasionally, just to sample something new, but they got a lot of work to do to match my homegrown!
That would be the main reason I grow my own. I know what is in it. If I was able to buy high quality bud that did exactly what I need, I would reconsider growing, but since I can't, here I am. The local here is selling what one stoner friend of mine says is good stuff for $125 Cdn/ounce. At that price, buying the stuff would be cheaper as well as a lot less work. However, my trials of dispensary weed have all been expensive disappointments. The commercial guys just don't seem to get it.
Another stoner friend of mine gave me a bud from his supplier's grow of Big Bud. It was ok, but unremarkable. Whatever, I broke off another piece to grind up, and to my shock, the inside of that bud was rotten before dried. How in hell my friend managed to not notice is a bit of a puzzle to me. I debated whether to tell him, but decided not to bother. Knowing him a bit, there is zero chance that he would toss the stuff if it did the job for him, and I doubt that his supplier would have admitted what was up with the bud.
Homegrown for me, period.