Are you looking to get into the battle royale craze for slightly cheaper? Activision Blizzard has got your back, as long as you're a PC player. Available on Battle.net, a $40 "Battle Edition" of the game will get you up and running in traditional multiplayer and "Blackout" mode. It is currently on sale for $30 until January 6, 2019.
The website reads, "The Black Ops 4 Battle Edition offers the full Multiplayer and Blackout experiences and is compatible with all existing copies and online lobbies for those modes on PC. For fans interested in getting their hands on even more, an upgrade to the Digital Standard Edition on PC—includes Zombies mode, 1,100 Call of Duty Points and Digital Edition bonus items—will also be available for purchase." At least you aren't locked out of zombies forever.
While zombies might be the best feature in Black Ops 4, I can see people wanting to focus on battle royale entirely. "Blackout" is great fun, even if I've grown a bit tired of the battle royale craze. With Treyarch saying it will receive updates outside of the season pass, this could be the cheapest option you have for getting into the fray.