This could be a different answer for every person that asks, but each semester there is a considerable amount of end-of-term processing that must occur before degrees can be posted. To ensure that your degree gets posted as soon as possible, please review your DARS or iPOS and work with your advisor to make sure all requirements are marked as complete. The majority of degrees are posted within 10-14 days of the degree conferral date.
It's common for universities to have a fee associated with graduation. The graduation fee pays for items such as the diploma, diploma case, honor cords, postage, mailers, etc.