We're also bringing free content packs, with a higher difficulty level, new character outfits, and much, much more. (gameondaily.com)
I purchase game add - ons, seasons passes and the odd weapon skin or character outfit from time to time, but I've never gone crazy with it. (n4g.com)
However, since then, they have introduced several different types of loot boxes, some of which cost real money to open, containing character outfits and weapon skins. (microtransaction.zone)