How do we get from Mogao Caves to Echoing Sand Dunes?

1. Are there any public transportation or do we need to take a taxi? And if we need to get a taxi, are taxis readily available at Mogao Caves? If we can take public transportation, what bus no. do we take?

2. Is the camel ride expensive? How do we avoid getting ripped off?

3. How do we get back from Echoing Sand Dunes to Shazhouyi International Youth Hostel?

Thank you in advance for answering my questions above!