What is a more affordable and faster way to get from Harbin to Hohhot?

According to your situation, you are suggested to get to the destination by plane.
The fares of flight or train don't have a big difference.
So you should choose the faster one. It takes around 2.5 hours on the way.

That period of time is an favorable season to enjoy a special and typical scenery there - Poplar Forest in Ejina.
With an area of more than 65,000 acres, poplar forest becomes an ocean of gold.
This is worth to see!