According to Blizzard's own words Diablo IV Gold, you don't have to pay for all of these items I'm guessing most people don't. However, you'll be forced to go through a lot of repetitive grind instead, and begin to think about how much of your precious time will be worth.
Diablo Immortal picks up where Diablo II began. To stop the demon Lord Diablo and his cohorts from attacking the fantasy realm of Sanctuary Tyrael, the archangel destroyed the Worldstone as an object of immense power. Now, the rest of the forces from Hell are searching for fragments of Worldstone to serve their own purposes. As a courageous adventurer, you join forces with frequent scholar Deckard Cain in order to find the Worldstone fragments and then destroy them, before a new demon lord named Skarn gets his hands on them.
I'm not sure about the plot of Diablo Immortal. On one hand, it has a lot of respect for the history of the franchise it picks up right where Diablo II left off and setting the stage for what's to come within Diablo III. There's more to learn about the civilizations and cities of Sanctuary and fans who have played for a long time will appreciate appearances by characters like Xul the Necromancer as well as King Leoric of Tristram.
However the story is a repetition that of Diablo II. You'll aid a camp of woodland rogues. You'll also reassemble a legendary staff to fight in the desert take on hostile Shamans in a swamp and climb a mountain with barbarians -If there's a game like Diablo II, you've literally experienced all of these before. The story beats in the new game consist of "find the MacGuffin; destroy this MacGuffin" repeated at least four cheap Diablo 4 Gold times. I'm also curious if Blizzard will follow the same formula for adding additional areas in the near future.