Hi, I am Marsha, I was stay In Lhasa from 2006/3/1 to 2008/2/15, I a guide for Tibet in 2 years, The frist you need a permit to go in Tibet, It is cost 200- 1000yuan RMB for one, dipend time and change you have, But untill now, it is not passible to go there, even full of May. Before to pay by any tickes please check and get enough informatons, If you want to go now, You even can not get Fly tickes !
good luck !
If you have any question you can call me 13187826923 !
You are welcome.
Have a good trip to you !