Most of the good black hash is exported.
I tried to track down some but no luck in it, also i was not there during the season.
I gathered as much info as I could, and was told this is available if you're ready to buy a Kg for around 4000$. No less than a kg, it's not possible.
I have come along some correct black hash twice, that seemed pure and bubbled a bit. It was really really nice and strong, but this was probably second quality. And i've seen 100's of different black ones (anytime i would see hash I'ld ask to have a look).
It seems that because most people coming have quite a light knowledge in Hash, they all get ripped of by poor quality/laced stuff, and now that is all what's available.
Even when I come along some nice pollen, there was a higher quality that was only available if you were ready to wait, knew where to ask, and get like a kg at least (mmm for 200$ seemed a fair price, still).
But most people will be more than happy to smoke the shit. I was not, that is why I kept doing some oil and waterhash. But there is definitely decent stuff around, especially in pollen and ganja, that is worth the trip. I'm a particular smoker, very very picky, that's why I'm telling you that you're not gonna find the one easily. Most people would say they found it, it's cause they don't know the real deal !
If you are going to Nepal you can ask me, I'll point you to some directions where to find THE goods, that you can already find in my Nepal thread. Pollen is the trick