If you played the beta, you no doubt opened plenty of loot boxes. These boxes contained four random items to customize your characters, such as new emotes, skins, and sprays. While you can still gain loot boxes from leveling up, you can also opt to spend money for more loot boxes.  The prices are as follows:

2 boxes - $1. 99 5 boxes - $4. 99 11 boxes - $9. 99 24 boxes - $19. 99 50 boxes - $39. 99

The boxes only contain cosmetic items, so players who spend money on the boxes won’t have a better change of winning, though they may have more stylish characters.  Blizzard has confirmed that they won’t be selling extra characters or maps as microtransactions as well.