No, no picture shooting allowed. and not everyone can go.
you gotta give ur "sheng1 cheng2 ba2 zhi4" to the master,
and after that the master will tell u if you are allowed to go,
as it's not a normal event, your spiritual/luck/energy what ever u called it,
might not able to take it.
you know? those ppls who running biz in tibet was descript as "tibet's you2 tai4 ren2", u should know what does it mean, if i were you, if they asked for RMB300, just ask them RMB200 at most, take it or leave it. they will say.... ok ... take it...
but not every tibetan behave like that...
tell them, give me a good price, i dun want to bargain with you, if the price is ok, i take it else u'll lose the business, and you only got 1 chance. then they will honest you.
or when u reach the place, ask around, how much does it cost from 1 place to another with local ppls. they can give u a better picture of how much u can ask.