It's weird - it's very hard to find 'Mexican dirt weed' these days, since all the medical dispensaries opened up. The medical stuff costs a little bit more, but it is way better. But you can't even find the old crap if you look.
I agree, though, that I haven't seen anything even remotely close to that garbage anywhere in the US in the last 10 years.
And the price for the really good stuff has actually come down a fair bit (10-30%) in the last ~5 years (especially in the last 2), even on the black market.