Although the costs of big video game releases such as The Last of Us franchise are rarely spoken about publicly by the developers, it’s possible to estimate how much The Last of Us 2 cost to produce. Generally, video games of this caliber and size run into the hundreds of millions of dollars. According to Eurogamer, Metal Gear Solid V: The Phantom Pain cost roughly $80 million, and that game was only in development for roughly three years compared to The Last of Us Part 2's six. The longer a game takes to release, the more expensive it becomes.
It’s not far-fetched to assume that The Last of Us cost even more than this, given how detailed and large the game is. The Witcher 3: Wild Hunt reportedly cost $46 million to develop, CD Projekt Red confirmed in 2015, but that's less than games of its scale usually do. Perhaps most revealing is the fact that both God of War – known for its incredible environments and graphical quality – and Shadow of the Tomb Raider have been estimated to cost upwards of $100 million to produce. Considering that The Last of Us Part 2 is a first-party Sony title, just like God of War, it would be realistic to put its development budget estimates near $100 million, if not even higher, considering the amount of time and effort it took to produce TLOU2.
While it's hard to nail down an exact price, by looking at past trends and other similar titles it's likely that The Last of Us Part 2 cost Sony at least $100 million to make, if not even more.