Dear sir/madam for Trekking visa till Tibet what will be charge for Europeans for group visa?

As I am from a Trekking agency from Nepal and I have some clients from Spain willing to have holy visit (around Kailash). It would be great pleasure for me if I would know the visa charge for group. In addition may I know the short process for acquiring the visa??

Sincerely yours,
Owngchu Sherpa