How much do it cost to tour Great Wall of Mutianyu

It is hard to tell you an exact price, because it depends on what kind of transportation to the wall and how to climb the wall.
If you can catch the special tourims bus line 867 from the Dongzhimen, the bus fare is around 16RMB for the whole journey. The entrance fare for the wall is 45RMB per person. Then if you do not use the cable, the fare in all is 61RMB. If you use the cable, the fee for cable car is 80RMB per person.