Minivans can be caught to and from Luding. They take about 2 hours. A bus can be taken directly to Chengdu at 7:00am.
The main reason to come to Moxi is to visit the nearby Glacier in Hailuogou Glacier Park. The entrance to the Glacier park is in Moxi but the Glacier itself is 30km out of town. After buying the entrance ticket for ¥85 you will need to buy a "sight seeing" bus ticket for ¥60. This can be misleading. The bus is really just a return ticket to and from the glacier. Don't try to walk! If you plan on cycling you will need the entire day and even then you may not make it there and back. There is a cable car to lookout over the glacier and a walkway up to the base of the Glacier.