Another consideration is feel. While everyone focuses on "soft silvertip," soft isn't actually for everyone. I personally like some scrub. And within both the soft and scrubby camp you will find a huge range of prices.
I have a $5 Marvy boar I use for traveling and brushes which cost way too much to admit. Both make a lather. With enough time, the $5 brush can make nearly as good of a lather as brushes costing many times more. So whats the difference you ask? Feel. For me, shaving is more than a necessity, it is a pleasure. The right badger brush adds exponentially to that experience for me.
That being said, if you are in this hobby to save money, then no, a $200 brush isn't worth it. A $40-60 brush will be almost as good. But to me, my brushes are worth every penny, as I enjoy them each and every morning. There are people here with 5, 10, or more brushes. I admit, I am one of those. But while someone may say, why is that necessary? The same could be asked of the scotch drinker with 50 whiskeys in his collection. That being variety.