Turpan To Dunghuang

Well, there is no direct long-distance buses between these two places.
You need to take bus to Hami Bus Station first. Only one schedule on 08:30 every day except Sunday. The referenced price is CNY 33 per person.
Then transfer a long-distance bus to Dunhuang. The different schedules are 07:00 in summer and 08:00 in winter. The ticket fare will change with seasons.