Unless you wind up with a really poor brush where the hair falls out in quick order most brushes expensive or cheap will do the job. It's like driving around in a Yugo or a BMW. Both will take you where you want to go.

The key points are; do you like the way it feels on your face? Do you like prickly and stiff or floppy and like a marshmallow or in between? Is it well made? Do you like the size of the handle and the fit in your hand? Does it slip in your hand when wet? Do you like the loft of the brush and amount of fill? Do you like the material the handle is made from? Are you particular about the overall appearance?

These factors will affect the cost and your satisfaction.