When people want to dress well even when playing basketball or football, the clothes worn have to fit the part. This means wearing something like Fubu, Nike or Reebok instead of some cheap knockoff that will get torn after a few washes.
The quality of the thread used plays a big part in the cost of the shirt. Discounts or sale events only happen when the season is about to end so if the person wants to be in style, the customer has no choice but to pay for it.